DRD4 (dopamine receptor D4) as the best potential genetic marker for childhood diagnosis and methylphenidate (MPH) response. Here, we aimed to provide additional evidence on biomarkers for ADHD diagnosis and treatment response, by using more specific approaches such as meta-analytic and bioinformatics tools. Via meta-analytic approaches including over 3000 cases and 16,000 controls, we demonstrated that, among the different variants studied in DRD4 gene, the 48-base pair, Variable Tandem Repeat Polymorphism, VNTR in exon 3 showed an age/population-specificity and an allelic heterogeneity. In particular, the 7R/“long” allele was identified as an ADHD risk factor in European-Caucasian populations , also, from the results of last meta-analysis, linked to the poor MPH efficacy. The 4R/“short” allele was a protective factor in European-Caucasian and South American populations , and was also associated to positive MPH response. These results refer to children with ADHD. No evidence of such associations was detected for adults with persistent ADHD . Moreover, we found evidence that the 4R allele leads to higher receptor expression and increased sensitivity to dopamine, as compared with the 7R allele , and this is consistent with the ADHD protection/susceptibility effects of the respective alleles. Using bioinformatics tools, based on the latest genome-wide association (GWAS) meta-analysis of the Psychiatry Genomic Consortium (PGC), we demonstrated that the 48 bp VNTR is not in Linkage Disequilibrium with the DRD4 SNPs (Single Nucleotide Polymorphisms), which were not found to be associated with ADHD. Moreover, a DRD4 expression downregulation was found in ADHD specific brain regions . Overall, our results suggest that DRD4 48 bp VNTR variants should be considered as biomarkers to support the diagnosis of ADHD and to predict MPH response, although the accuracy of such a biomarker remains to be further elucidated.The identification of biomarkers to support the diagnosis and prediction of treatment response for attention-deficit/hyperactivity disorder (ADHD) is still a challenge. Our previous works highlighted the  The worldwide prevalence among school-aged children is around 5%2. About 65% of affected individuals continue to exhibit impairing ADHD symptoms into adulthood3. ADHD prevalence in adults is estimated at 2.5%4.Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder, characterized by age-inappropriate symptoms of inattention and/or hyperactivity-impulsivity, with a heterogeneous clinical phenotype5. Moreover, changes in structural brain abnormalities from childhood to adulthood with ADHD have been reported6, suggesting potential differential causes for the onset and persistence of the disorder7.The severity level and presentation of ADHD changes over the lifespan, with adult patients displaying less obvious symptoms of hyperactivity and impulsivity9, in childhood and at 30–50%12 or even greater14 in adulthood. The most recent and largest genome-wide association (GWAS) meta-analysis from the Psychiatric Genomics Consortium (PGC) identified common single-nucleotide (SNPs) variants, surpassing genome-wide significance in 12 independent loci15, providing important new insights into the neurobiology of childhood ADHD. Additional insight comes from the studies on the crucial role played by rare variants9.ADHD aetiology is not yet completely understood. Despite evidence that environmental factors  play a significant role, genetic studies support a strong genetic contribution. Indeed, average heritability was estimated at 76%16. Taking into account both efficacy and safety, evidence from a recent network meta-analysis17 supports methylphenidate (MPH) in children and adolescents, and amphetamines, in adults, as possible first-choice medications for the short-term treatment of ADHD, suggesting once again potential neurobiological differences across the lifespan.Pharmacotherapy is a crucial component for the treatment of ADHD19 and is responsible for neuronal signalling in the mesolimbic system of the brain. It is specifically involved in dopamine synthesis, release and neuronal firing18. It has been considered a candidate for the aetiology of ADHD due to its high expression in brain regions implicated in attention and inhibition, such as the orbitofrontal and anterior cingulate cortex21. Additional interest derived from a link with the personality trait of novelty seeking23, which has been compared with the high levels of impulsivity and excitability often seen in ADHD24. Further, the DRD4 “knockout” mouse exhibits a heightened response to cocaine and methamphetamine relative to controls, as indicated by increases in loco-motor behaviour25. The DRD4 gene comprises four exons and encodes a putative 387-amino acid protein with seven transmembrane domains, where the most widely studied 48 bp VNTR (variable tandem repeat) polymorphism encodes the third cytoplasmic loop. This multiallelic polymorphism includes 11 copies of a 48-bp repeat sequence, where the 4, 7 and 2 repeat (R) alleles are the most prevalent. Genetic demographic studies report that the 7R allele is present in highly varying percentages in different populations worldwide30. It is known that this polymorphism impacts on mRNA and protein expression levels, indicating a significant functional biological effect of this polymorphism on the translation of the respective protein31. After the exon 3 VNTR, the other DRD4 polymorphisms studied are found in the promoter region of the gene: 120 bp duplication (rs4646984); −521 C/T (rs1800955), −616 C/G (rs747302); 12 bp (rs4646983), −615 A/G (rs936462), −376 C/T (rs916455).In the era of precision medicine, the biomarker approach to diagnosis and treatment offers the opportunity to improve diagnostic assessment and provides insights into etiological mechanisms. As it is known that a considerable proportion (35%) of ADHD patients do not respond to available first line medication, this approach has also the potential to contribute to individualized therapies. The DRD4 (dopamine receptor D4) is a G-protein-coupled receptor belonging to the D2-like receptor family, which modulates intracellular signalling by inhibiting the production of the second messenger cyclic AMP (cAMP) level33, we strongly suggested that DRD4 along with dopamine transporter gene (SLC6A3) are significant predictors of childhood ADHD susceptibility, different endophenotypes, MPH response, and linked to altered genes expression levels. However, the latest GWAS/meta-analysis15 did not detect associations with these “classical” candidate genes.In our previous worksDRD4, to further assess its role as a potential biomarker for the diagnosis of ADHD and for MPH response, both in children and adults. Up-date and new meta-analyses were performed to statistically assess the association with ADHD in childhood and to confirm the functional role of the 48 bp VNTR. Bioinformatics in silico analyses were conducted to understand the impact of DRD4 gene and of 48 bp VNTR polymorphism in the pathology and to reconcile our positive findings with the negative results for five DRD4 SNPs in the GWAS of Demontis et al.15. We used also bioinformatics tools to confirm the functional role of DRD4 in specific ADHD brain regions. In addition, after the literature research on the association between DRD4 polymorphisms and ADHD susceptibility in children with ADHD and MPH response in ADHD adulthood, we concluded that there are not enough studies to perform meta-analyses.Here, we build on and expand our previous studies, focusing on So far as the literature research does not add further studies to the meta-analytic approach, we reported the results from the last more recent meta-analyses, and this regards the associations of SNPs and ADHD susceptibility in children with ADHD, as well as the 48 bp/SNPs with ADHD susceptibility in adulthood and with MPH response in ADHD childhood and adulthood.34, we searched the electronic databases PubMed, Embase and “ADHDgene Database” (http://adhd.psych.ac.cn/), up to December 2018, with no restrictions on language, date, or article type. In PubMed, we used the following search terms/syntax “ADHD OR attention deficit OR attention-deficit OR attention deficit hyperactivity disorder OR attention-deficit hyperactivity disorder OR hyperkinetic syndrome OR hyperkinetic disorder OR hyperactivity disorder OR hyperactive child syndrome” AND “children OR child” AND “DRD4 OR dopamine receptor D4, AND “gene”, AND “polymorphisms”, AND “SNP OR Single Nucleotide polymorphism”, AND “VNTR OR variable tandem repeats”, AND “association”, AND “TDT OR Transmission Disequilibrium Test, OR family-based” AND “methylphenidate OR MPH”, AND “pharmacogenetics”, AND “drugs”, AND “treatments”, AND “clinical trials” AND “meta-analy* OR metaanaly*”. During the research, we identified different meta-analyses, however we took in consideration those more recent: Gizer and colleagues35, Wu and colleagues36; Nikolaidis and Gray37; Myer and colleagues38, to cross-check their references to find any publications possibly missed in our electronic search. The literature search was performed independently by two individuals . Disagreements were resolved by the other authors.According to the PRISMA guidelines39.The Newcastle-Ottawa Scale was used to assess quality of studiesWe selected articles that met the following inclusion criteria: ADHD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders  or equivalent Hyperkinetic disorder or the International Classification of Diseases 10th Revision (ICD-10) or previous versions; case–control and a family-based study design for genetic studies; clinical trials for pharmacogenetic studies. We excluded studies (a) using comparisons with a family control ; (b) using samples fully overlapping with other included studies; (c) for which data to perform analyses were not available, even after contacting the study corresponding authors.CS and CB independently extracted the following data: first author, study design, year of publication, populations studied, study design, sample size, ethnic groups, and key results from each study.z-tests. Between-study heterogeneity was assessed using a χ2 test of goodness of fit test and the I2 statistic. We used a P-value < 0.05 to indicate statistical significance.Review Manager was used to perform the meta-analysis . We used the random-effects model to generate a pooled effect size and 95% confidence interval (CI) from individual study effect sizes . The significance of the pooled effect sizes was determined by 40 which relies on a linear regression approach to measure funnel plot asymmetry on the natural logarithm scale of the effect size. The significance of the intercept (a) was determined by the t-test40. The rank correlation method and regression method tests were conducted using MIX version 1.7 .Publication bias was estimated using the method by Egger and colleagues31, we divided these repeat alleles also into “short” (two to four) and “long” (five to eight)43 and conducted the meta-analyses considering “long” allele versus others.In relation to 48 bp multiallelic variants, the meta-analyses were conducted comparing 7R versus others, 4R allele versus others and 2R alleles versus others. Based on different pharmacological characteristics44, and we reported their findings, because no additional studies have been performed.Search strategy and selection criteria, inclusion and exclusion criteria, and statistical analyses were conducted as above, except for the term “adults” instead of “children OR child”. During the research, we identified the most recent meta-analysis45 to find any publications possibly missed in our electronic search and did an updated search through to December 2018. We performed meta-analyses for 2R allele versus 4R, 2R versus 7R and 4R versus 7R. Statistical analyses were conducted as above.We cross checked the references of the latest review describing the different studies on the functional biological effect of the 48 bp VNTR polymorphism15  are included, we built a population specific-linkage disequilibrium (LD) block by using Haploview software.From 1000 Genome database in which the five SNPs found negative in last GWASDRD4 on ADHD aetiology we performed a Transcription Wide Association Study (TWAS) considering the last available summary statistics for ADHD in the PGC portal (https://www.med.unc.edu/pgc/). TWAS is a gene association method estimating whether a different gene expression regulation  could be expected for the analysed phenotype based on GWAS associations. This can be done through the imputation of the genetic component of gene expression using tissue-specific cis-eQTL models46. In our analysis, we considered cis-eQTL models (http://predictdb.org/) trained on the Genotype-Tissue Expression database, i.e., GTEx  and we specifically focus on brain tissues.With the aim to further investigate the involvement of The PRISMA flow chart is in Supplementary Fig. We structured this paragraph reporting the results in relation to (a) the comparisons using as dependent variable the allele comparison ; (b) merged data between the two genetic approaches: CC and TDT studies for alleles 2R, 4R, 7R; (c) publication bias and (d) Newcastle-Ottawa Scale.The results are showed in Supplementary Fig. In Asian populations: (a) CC: Random model Z = 0.27, P = 0.79, in presence of heterogeneity in effect size across the studies: P = 0.005, I2 = 60%; (b) TDT: Random model Z = 0.04, P = 0.96, in absence of heterogeneity in effect size across the studies: P = 0.56, I2 = 0%.In European-Caucasian populations: (a) CC: Random model Z = 0.56, P = 0.57, without heterogeneity in effect size across the studies: P = 0.06, I2 = 39%; (b) TDT: Random model Z = 1.40, P = 0.16, without heterogeneity in effect size across the studies: P = 0.47, I2 = 0%.In Middle Eastern populations: (a) CC: Random model Z = 0.79, P = 0.43, with heterogeneity in effect size across the studies: P < 0.0001, I2 = 84%; (b) TDT: Random model Z = 0.23, P = 0.82.In South American populations: (a) CC: Random model Z = 0.61, P = 0.54, without heterogeneity in effect size across the studies: P = 0.12, I2 = 49%; (b) TDT: Random model Z = 0.82, P = 0.41.The results are showed in Supplementary Fig. In Asian populations: (a) CC: Random model Z = 0.04, P = 0.97, without heterogeneity in effect size across the studies P = 0.11, I2 = 36%; (b) TDT: Random model Z = 1.78, P = 0.07, with heterogeneity in effect size across the studies P < 0.00001, I2 = 90%.In European-Caucasian populations: (a) CC: Random model Z = 3.31, P = 0.0009, d = 0.79 95%CI: 0.69–0.91, with slightly heterogeneity in effect size across the studies P = 0.02, I2 = 48%; (b) TDT: Random model Z = 1.08, P = 0.28, with slightly heterogeneity in effect size across the studies P = 0.01, I2 = 55%.In Middle Eastern populations: (a) CC: Random model Z = 0.31, P = 0.76, with heterogeneity in effect size across the studies P < 0.00001, I2 = 87%; (b) TDT: Random model Z = 0.72, P = 0.47.In South American populations: (a) CC Random model Z = 1.66, P = 0.10, with no heterogeneity in effect size across the studies P = 0.08, I2 = 50%, (b) TDT: Random model Z = 0.00, P = 1.00.The results are showed in Supplementary Fig. In Asian populations: (a) CC: Random model Z = 0.46, P = 0.65, without heterogeneity in effect size across the studies P = 0.77, I2 = 0%; (b) TDT: Random model Z = 0.35, P = 0.72, without heterogeneity in effect size across the studies P = 0.60, I2 = 0%.In European-Caucasian populations: (a) CC: Random model Z = 2.77, P = 0.006, d = 1.25 95%CI: 1.07–1.45, with heterogeneity in effect size across the studies P < 0.00001, I2 = 75%; (b) TDT Random model Z = 5.09, P < 0.00001, d = 1.40 95%CI: 1.23–1.59 in absence of heterogeneity in effect size across the studies P = 0.25, I2 = 16%.In Middle Eastern populations: (a) CC: Random model Z = 3.13, P = 0.002, d = 0.61 95%CI: 0.45–0.83 in absence of heterogeneity in effect size across the studies P = 0.50, I2 = 0%; (b) TDT: Random model Z = 0.63, P = 0.53, in absence of heterogeneity in effect size across the studies P = 0.11, I2 = 61%.In South American populations: (a) CC: Random model Z = 1.59, P = 0.11, with a trend in heterogeneity in effect size across the studies P = 0.03, I2 = 57%; (b) TDT: Random model Z = 0.10, P = 0.92, in absence of heterogeneity in effect size across the studies P = 0.65, I2 = 0%.The results are showed in Supplementary Fig. In Asian populations: (a) CC: Random model Z = 1.01, P = 0.31, in absence of heterogeneity in effect size across the studies P = 0.43, I2 = 1%, (b) TDT: Random model Z = 0.94, P = 0.35, in absence of heterogeneity in effect size across the studies P = 0.19, I2 = 35%.In European populations: (a) CC: Random model Z = 4.04, P < 0.0001, d = 1.41 95%CI: 1.19–1.67, in presence of heterogeneity in effect size across the studies P = 0.005, I2 = 54%, (b) TDT: Random model Z = 2.49, P = 0.01, d = 1.28 95%CI: 1.05–1.56, in absence of heterogeneity in effect size across the studies P = 0.10, I2 = 37%.In Middle Eastern populations: (a) CC: Random model Z = 2.32, P = 0.02, d = 0.62 95%CI: 0.41–0.93, with a trend of heterogeneity in effect size across the studies P = 0.04, I2 = 56%, (b) TDT: Random model Z = 0.76, P = 0.45, with heterogeneity in effect size across the studies P = 0.01, I2 = 85%.In South American populations: (a) CC: Random model Z = 1.05, P = 0.29, in absence of heterogeneity in effect size across the studies P = 0.19, I2 = 38%, (b) TDT: Random model Z = 0.49, P = 0.62.Table Z = 3.08, P = 0.002, d = 0.83 95%CI: 0.74–0.94, in presence of heterogeneity in effect size across the studies P = 0.0009, I2 = 52%). The statistical power increased when we combined the European-Caucasian with South American populations . Allele 7R was found associated in the European-Caucasian populations .The association with ADHD susceptibility was confirmed for allele 4R in European-Caucasian populations , but with a protective effect in Middle Eastern population .Concerning the results for the “long” allele, we found associations with ADHD susceptibility in European-Caucasian populations (Random model P = 0.018), with higher values when the CC and TDT findings were combined (P = 0.0004). Of note, we observed that, when we eliminated from the analyses the manuscripts from Sonuga-Barke and colleagues47 (P = 0.02) along with Altink and colleagues48 (P = 0.08), the values are less significant and the P value for the total sample was 0.83.The results of Egger’s test for publication bias are reported in Supplementary Table Analyses of the “long” and 4R alleles showed no publication bias.In Supplementary Table 36. Thus, the results did not change for the 120 bp duplication (rs4646984); −521 (C/T) (rs1800955); −616 (C/G) (rs747302), 12 bp (rs4646983); −615 (A/G) (rs936462); −376 (C/T) (rs916455), that did not show significant results.Besides the VNTR, several SNPs were investigated. Our research did not add any other studies reported in the last meta-analysis by Wu and colleagues51; rs464698452; rs91645753; rs93646554, no-meta-analyses can be performed, because very few studies were available (minimum three studies), considering that Yu and colleagues50 and Chang and colleagues51 studied the same population.For other SNPs: rs7395429, rs3758653, rs11246228, rs75230638 on 48 bp VNTR. Thus, we reported their results and their analyses. In particular, the homozygous 4R genotype demonstrated an association with improved MPH response, when compared with other genotypes , whereas the meta-analysis of the 7R repeat allele versus others showed a trend with an OR = 0.68 38.Regarding to the research on the MPH pharmacogenetic studies, we ascertained that no other new studies were published on this topic as compared with the last meta-analysis by Myer and colleagues44, no other studies on the topic were available to add to the analyses. Concerning 48 bp VNTR, no association was observed. Contrasting results have been reported for the 120 bp duplication (rs4646984) and negative results for rs3758653, and rs936465. In relation to those retrieved in the most recent meta-analyses44, no other additional studies were found.From the last meta-analysis44.Concerning 48 bp VNTR, two studies were available with negative results and one study on 120 bp duplication45, that resumed the studies on the potential biological differences among DRD4 VNTR variants, was updated and, because no other new studies were conducted since 2014 to date, we conducted meta-analysis on the papers reported in Pappa and colleagues45. The studies are divided according to in vitro, in vivo and in silico methodologies. There were enough studies (minimum three studies) to perform meta-analyses only for in vitro studies and they were divided according to technologies used: [3H]spiperone binding RIA; [3H]spiperone Ca2+ channel flux assay; [35S]GTPγS agonist stimulated binding assay; BRET50 assay; luciferase reporter assay; western analysis; transient transfection. In Table Z = 4.52; P < 0.00001, d = 0.86 95%CI: 0.48–1.23); allele 2R versus 7R  and allele 4R versus 7R , respectively. These results showed evidence of decreased functionality of the 7R compared with the 2R and the 4R.The last review by Pappa and colleaguesDRD4 gene LD blocks for different populations . We found that the 48 bp VNTR was not tagged by any of the GWAS SNPs used by Demontis and colleagues15  with DRD4 due to a downregulation of gene expression in a specific brain area, which is the Putamen region included in Basal Ganglia .According to the brain tissues filter, the analysis showed a nominally significant association  factor in children with ADHD, whereas our previous data44 supported no association in ADHD adulthood in general population.In our prior reviewSLC6A3 gene55 where allelic variants showed differential effects in children and adults with ADHD, these findings suggest that DRD4 and SLC6A3 are among those genes that account for developmental variations with differential effects across the lifespan.As associations were observed also for the 15, five SNPs in DRD4 were not significant according the GWAS cut-off significance (10−8). In this work, we show that those findings do not contradict our conclusions on the role of DRD4 in ADHD, because none of the SNPs assayed in that study15 are in LD with the 48 bp VNTR. Thus, the role played by the DRD4 in ADHD susceptibility is determined predominantly by the 48 bp VNTR variants.From the last SNPs/GWAS meta-analysisDRD4 VNTR displays a high degree of variability across populations worldwide, e.g. 48% in native Americans, but only 0–2% in Asians. There is no commonly accepted explanation for this variability at the DRD4 locus. A recent review56 suggested that the common and probably ancestral allele has four repeats, originating 300,000 years ago, whereas the 7R allele is up to 10 times younger. The 7R allele may have arisen as a rare mutational event and then become a high frequency allele by positive selection at a time of the major expansion of human population . In this way, individuals with novelty-seeking personality traits may have driven the expansion of the 7R variant, or it may have conferred a reproductive advantage in male-competitive societies. In the Americas, an increase in the 7R allele may have been due to a successive founder effect, and in China a decrease in the 7R may have been due to selective reproduction of males without the 7R allele. At the same time, there appears to be selective forces working to balance the alleles in modern societies , and the prevalence of the 7R allele may now be at a stable level or near a fixation point56.The population-specific allelic heterogeneity we found is consistent with prior reports that the 57.Polymorphisms within key monoaminergic genes have been associated with the response to stimulant medication, albeit through conflicting evidence. This is mechanistically intuitive as MPH modulates extracellular catecholamine levels through interaction with dopaminergic, adrenergic and serotonergic system components. MPH inhibits catecholamine reuptake and modulates dopamine and norepinephrine levels, by binding to and blocking dopamine and norepinephrine transporters, thereby increasing extracellular concentrationsDRD4 48 bp VNTR38 reported a significant association between MPH efficacy and the 4R allele. ADHD children with 4R/4R genotypes showed a 66% increased chance for efficacious MPH response; compared with others, where the efficacy measure was defined by changes at Clinical Global Impression-Improvement (CGI-I) and Severity (CGI-S), and ADHD Rating Scale (ADHD-RS), whereas the 7R allele versus others did not reach significant association, even though a trend towards to poor MPH response was observed38. Thus, these data are in line with the European susceptibility/protection role of 7R“long”/4R alleles, respectively. This is also consistent with the evidence that, as already evidenced, the 4R leads to higher receptor expression and increased sensitivity to dopamine, as compared with the 7R variant. MPH works by blocking the pre-synaptic dopamine transporter, thus increasing synaptic dopamine58. Since 7R shows weaker transduction effects, the response to an increased level of synaptic dopamine will be weak31. These results further implicate that the children with ADHD homozygotes for 4R alleles would require lower doses of MPH to achieve symptom improvement.The most recent pharmacogenetics meta-analysis on the 59. Only half of children with ADHD followed pharmacological treatment regimens consistently over the course of a 5-year prospective study, and many reported adverse effects, and also the perceived tolerability may also be an impediment to adherence to treatments. Myer and colleagues38 analysed DNA variants in different genes linked to the effectiveness of MPH treatment. Leveraging individual genetic variants within not only DRD4 but also in SLC6A2, COMT, ADRA2A and SLC6A3 the authors presented a plausible multivariate to assess risk for poor MPH efficacy. It is possible that, as they suggest, a multivariate predictor would be sufficiently accurate for clinical use. Furthermore, collectively evaluating genetic variability among plausible biological markers for treatment success would eliminate trial-and-error treatment used today60.The identification of predictors of pharmacotherapy is needed and always in development, to further the clinical implementation of precision medicine. Of note, patients receiving precision treatment were found to be more medication adherent37, some studies are not based on pure populations: i.e., refs. 74 are primarily European-Caucasian (about 80%), but the remaining percentage of the sample also contain other ethnic groups , are some reasons for the presence of heterogeneity. Moreover, even though we conducted the analyses taking into consideration different populations996–2018,45). We defined “short” allele (to 2R from 4R), and “long” allele (to 5R from 8R), a choice also confirmed by our data because the results did not change, as compared with the 4R and 7R analyses, respectively.Other important sources of heterogeneity are linked to how the genotypic classification of alleles was conducted in different studies. Some used 7R carriers vs. non-carriers, others: (2–5) vs. (6–11) repeat carriers; (2–6) vs. (7–11) repeat carriers;  vs.  genotypes; 2–4 vs 5–11R carriers .Finally, a TDT study design results significantly less heterogeneous than a CC study. Thus, we suggest conducting the meta-analyses, taking in consideration study design , but the P value becomes smaller (P = 0.0004) when CC model is merged with TDT study design. We observed that, when we eliminated from the analyses Sonuga-Barke and colleagues47 along with Altink and colleagues48, the values are less significant and the P value for the total sample was 0.83. This could further mean the importance of studying this kind of polymorphism in samples where there are not mixed populations.Regarding the results from Egger’s test, for the 7R case, we observed presence of publication bias in European populations with a CC model (DRD4 48 bp VNTR could influence the ADHD susceptibility as well as the MPH response across the lifespan, with differential associations depending on age and populations. Interestingly, as compared with the other common SNPs variants, this VNTR polymorphism shows a significant impact on the pathophysiology of ADHD.Our data strongly suggest that DRD4 both in ADHD children72, and in adults75 that needed further investigation.The advent of the new and high-throughput technologies such as next generation sequencing are contributing to better elucidate the implication of the rare variants on the ADHD susceptibility: interestingly it has been observed an increased burden of rare variants inside the 7R allele of 38 to the MPH response that could be sufficiently accurate for clinical use.In the era of precision medicine, the identification of biomarkers associated to diagnosis and treatment represents a valid way to classify complex mental disorders such as ADHD and offers the opportunity to standardize and improve diagnostic assessment, provide insights into etiological mechanisms, and contribute to developing individualized therapies. Although biomarkers are successfully used in predicting diseases such as cancer, there is no lab test that is used clinically for the diagnosis of ADHD. While there are several pharmacological treatments for ADHD, the mechanisms of action of these agents are still unclear and no specific biological predictors of treatment response are available. We here want to strength the added value provided by the biomarker identification approach for ADHD, and even though future work is needed, we speculate that 7R and 4R alleles of the 48 bp VNTR can contribute to improve the diagnostic picture with their specificity to childhood ADHD and to be a further actor in that possible multivariate predictorSupplementary Fig. S1Supplementary Fig. S2Supplementary Fig. S3Supplementary Fig. S4Supplementary Fig. S5Supplementary Fig. S6Supplementary Fig. S7Supplementary Fig. S8Supplementary Fig. S9Supplementary References for Table 4Supplementary References Table 1Supplementary Table S1Supplementary Table S2Supplementary material Legends


Attention is a central component of cognitive and behavioral processes and plays a key role in basic and higher-level functioning. Posner’s model of attention describes three components or networks of attention: the alerting, which involves high intensity states of arousal; the orienting, which involves the selective direction of attention; and the executive control, which involves cognitive functions such as conflict resolution and working memory. The Attention Network Test (ANT) is a computerized testing measure that was developed to measure these three networks of attention. This project describes the ANT, its widely used variants, and the recently developed ANT Database, a repository of data extracted from all studies that have used the ANT as of 2019. To illustrate the potential uses of the database, two meta-analyses conducted using the ANT Database are described. One explores task performance in children with and without attention deficit/hyperactivity disorder (ADHD). The other one explores regional differences between studies conducted in China, Europe, and the United States. We are currently in the process of integrating the database into a publicly available web interface. When that work is complete, researchers, clinicians, and the general public will be able to use the database to explore topics of interest related to attention. The development and maintenance of attentional capacity is central to cognitive performance. Attentional functioning plays a crucial role in task performance in the daily facets of life, and impairments in attention are present in a multitude of psychiatric disorders such as Alzheimer’s, Parkinson’s, stroke, and schizophrenia . In a seThe Attention Network Test (ANT) is a tool developed in 2002 by One component of attention is the alerting network, which corresponds to the achievement and maintenance of an alert and vigilant state. Activation in the right frontal and parietal hemispheres in the brain occurs when completing tasks that involve the alerting network . In the Orienting is the ability to selectively attend to a sensory pathway. Overt orienting involves sensory–motor engagement to stimuli, such as the redirection of head and eye movements . Covert Executive control is a term that encompasses many functions, such as problem solving, decision making, self-regulation, and conflict resolution. The ANT targets the latter of these by measuring the participant’s ability to ignore distractor stimuli. This component of attention presents with activation in the anterior cingulate gyrus and dorsolateral prefrontal cortex . NetworkFollowing the development of the ANT, a number of variants of the task emerged. The Attention Network Test for Interactions (ANT-I) introduced an auditory stimulus  to generate alerting and made the peripheral cue uninformative. The implementation of the auditory cue was designed to allow exploration of the interaction between the alerting and orienting networks . The useA multitude of other variations to the ANT have been developed in subsequent years. The L-ANT or Lateralized ANT was first developed in 2008 by In our initial exploration (in 2016) of the impact and prevalence of the ANT, over 2,000 articles were identified that had cited the seminal Fan et al. paper. We then sought to explore how many participants had participated in experiments using this testing measure or one of its variants to explore the growing interest in the use of this tool . This prNotably, at its current iteration, the database has been collated from over 3,000 studies that have cited the seminal ANT paper. The purpose of this paper is to describe this database and to illustrate its usefulness with some examples. It is our plan to make the database available to researchers, clinicians, and the general public via a web-based interface, the development of which is underway. This resource has allowed us to conduct two meta-analyses to date: explorations of attentional performance in children with and without attention deficit/hyperactivity disorder (ADHD), and regional differences in attentional processing between participants residing in China, Europe, and the United States. As previously described in The ANT Database was generated using the PubMed, Google Scholar, and Web of Science search engines with a comprehensive search of articles that had cited the original http://attentionnetwork.ca/.Data extraction was completed manually, and information pertaining to the purpose of the study, participant demographics, condition or clinical subset, number of participants in each condition, geographical region, and version of the ANT were entered into a spreadsheet. Error rates, mean RTs, and corresponding standard deviations/errors were extracted when provided. RTs and standard deviations/errors were extracted from the results section, supplementary tables, and, if not provided in the text, data figures using the WebPlotDigitizer, a web-based extraction tool . To dateA meta-analysis was performed on studies having conducted research with a clinical population of children with a diagnosis of ADHD and matched neurotypical healthy controls. Children with ADHD present with symptoms of consistent challenges with sustained attention, hyperactive behavioral tendencies, and challenges in organization and short-term memory consolidation.Despite the concerns of increased rates of ADHD that have been brought forth, the prevalence of children who meet diagnostic criteria has been shown to be relatively consistent over the past three decades across major geographical regions . HoweverImpairments in executive functioning have been proposed to be associated with ADHD over the past three decades . ChildreThis meta-analysis consisted of response time data (accuracy data were reported by too few studies) from studies that had both a control and an ADHD group, with participants in both groups ranging from 6 to 13 years of age. One study, Mean age weighted by the number of participants in a study was calculated for the ADHD group (10.8 ± 1.58 years) and the control group (10.6 ± 1.53 years). Forest plots for each study in this meta-analysis are presented in The hierarchical model also permits quantification of heterogeneity between studies for each measure, reflecting how much the studies differ from one to another over and above mere measurement error. Such differences would be attributable to unmodeled differences between the studies’ respective methods  or sample populations . Accounting for this heterogeneity is one of the primary benefits of the hierarchical model employed here, and this modeling choice is validated to the degree that the posterior distribution on the heterogeneity parameter is shifted away from zero. The findings from our ADHD meta-analyses are consistent with Using the ANT-I , In structural MRI studies, brain regions associated with the alerting and executive networks have been shown to be different in individuals with ADHD . The orbDifferences in linguistics and parental interactions have been shown to exist across cultures. The orienting network develops as a function of socialization within culture and community. Executive functioning, which involves the voluntary facilitation of attention, has apparent connections to an individual’s cultural environments . Given tThis meta-analysis explored cross-cultural differences in the three networks of attention. Regions in which the studies were conducted were identified through the methods section of each paper. Studies that had used the ANT were then grouped together by region and matched by age and number of participants. This resulted in 27 studies in total and nine from each region . Each region had a combined number of 330 ± 5 participants. A detailed breakdown of the demographics and sources for this meta-analysis is presented in Mean age, weighted by the number of participants in a study for China (37.2 ± 8.57), Europe (33.9 ± 7.55), and the United States (32 ± 9.4), was similar across all three regions. Forest plots for each study in the cross-cultural meta-analysis are presented in As in the previous application, quantitative inference was achieved through a Bayesian hierarchical model, coded and sampled using Stan . Each coThe posterior distributions for each measure and region are shown in The differences in the cross-cultural exploration have intriguing epistemological implications and suggest regional variations in attentional processing. Consistent with the suggestion  that aleAnalytical vs. holistic thinking style differences may account for the variations in the executive networks found in this meta-analysis. Chinese participants have been shown to have a higher sensitivity to discrepant stimuli , whereas European participants have increased P3 responses to designated target events . This diAs illustrated by the two applications presented here, this database has a broad reach and can be utilized for many meta-analytic explorations. It is our intention to further develop and maintain this database and make it accessible for public use through a web interface. This resource will present users with public health information pertaining to attention and how it is affected in a multitude of clinical conditions and by various experimental manipulations . In the impetus for open science, the ANT Database will allow users to conduct meta-analyses on topics of their interest by centralizing the data extracted.As the meta-analytic explorations conducted through the database have been through the secondary use of data, various limitations are present. Participants in the regional explorations had been selected from the control condition of a multitude of studies, for which differences in task implementation cannot be controlled. Variables such as socioeconomic status and participant age may also play a role, while general age across the three regions was relatively consistent. Within the ADHD exploration, studies consisted of experiments that had participants from both conditions, who were roughly the same age (10.6 and 10.8), and who would have experienced identical tasks. However, standard deviation or error was not reported in all studies. While the stand-in standard deviation calculated from the remaining studies served as an adequate estimate, there is room for error in this approximation.The applications and utility of the database are extensive, and it can be a useful tool for conducting further meta-analyses and providing a resource to attention researchers, clinicians, and knowledge users. In older adults, attention performance has been shown to deteriorate with age, and impairments in visual attention are predictive of other cognitive and neurological decline . While pThe next step in this project will be to further develop the web interface of the database. Our initial focus will be to continue the data extraction of the remaining studies and bring the database up to date; however, future directions will be to create a tool for public health and global applications of attention. This interface will provide clinicians, patients, and interested parties a centralized resource and detail recent findings on topics of interest identified by public users that will be highlighted on the web interface. This resource will minimize the expenditure of researchers and clinicians to provide literature and resources to patients with attentional impairments, provide information to knowledge users in an easy-to-interpret way, and foster interdisciplinary and community collaboration.https://osf.io/edfqn/). The web interface for the ANT Database described in this manuscript is hosted at http://attentionnetwork.ca (presently under development).The data sets and analysis scripts for this study are available at (Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.RK and SA contributed to the conception and design of this project. This research was conducted by SA under the direct supervision, guidance, and support of RK. ML performed statistical analysis and modeling of the data. All authors contributed to manuscript revision, and read and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The association of dietary inflammatory index (DII®), as an index of inflammatory quality of diet, with cardiometabolic diseases (CMDs) and risk factors (CMRFs) has been inconsistent in previous studies.The current systematic review and dose–response meta-analysis was performed to investigate the association of the DII score with CMDs and CMRFs.All published observational studies  using PubMed/Medline, Scopus, ISI Web of Science, and Google Scholar databases were retrieved from inception through November 2019.Two reviewers independently extracted the data from included studies.Pooled hazard ratio (HR) or odds ratio (OR) were calculated by using a random-effects model.nonlinearity < 0.001). Moreover, evidence of none-linear association between the DII score and risk of CMDs was not observed .Ten prospective cohort studies  with 31,069 CMDs-specific mortality, six prospective cohort studies  with 1311 CMDs-specific morbidity, two case–control studies with 2140 cases and 6246 controls and one cross-sectional study  with 1734 CMDs-specific morbidity were identified for CMDs. Meta-analyses of published observational studies demonstrated that the highest DII score category versus the lowest DII score category was associated with 29% increased risk of CMDs mortality  1.18, 1.41). Moreover, there was a significant association between the DII score and risk of CMDs in cohort studies  and non-cohort study . We found a significant association between the DII score and metabolic syndrome (MetS) , hyperglycemia and hypertension. None-linear dose response meta-analysis showed that there was a significant association between the DII score and risk of CMDs mortality (PAdherence to pro-inflammatory diet was associated with increased risk of CMDs, mortality and MetS. Chronic inflammation happens through frequent stress factors such as poor diet and obesity  and it iThe dietary inflammatory index (DII) is a novel and validated tool designed in 2009  and updaMultiple studies have assessed the association of the DII score with different chronic diseases –18 and tGiven the inconsistent findings, this meta-analysis was conducted to summarize the association of DII with CMRFs and CMDs in observational studies.Although recently some systematic reviews and meta-analyses have addressed the association between the DII score and CVDs morbidity and mortality –35 and MWe followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement for reporting in the current systematic review and mate-analysis study  and CMDs  according to the International Classification of Diseases (ICD)-9-390-465) were included through comprehensive searches on PubMed and the NLM Gateway (for MEDLINE), Scopus, and Institute of Scientific Information (ISI) electronic databases up to February 2020. The appropriate medical subject headings, Entry Terms, and Emtree options were applied to carry out the most sensitive search operations. The search strategy is presented in Additional file Two reviewers (ZA and HA) independently reviewed and screened the appropriate published papers based on title, abstract, and full text. The third reviewer (MQ) resolved any discrepancy in choosing eligible records. All observational studies  on human subjects without restriction of age group, gender, year of publication, and language examining the association between the DII score with CMRFs  and CMDs were included in the current study.The papers with the following conditions were excluded: (1) studies that considered the DII as a dependent variable, (2) letters, abstracts and reviews, and (3) duplicated publications. For multiple publications of the same population, only the article with the largest sample size was included.The participants, intervention, comparators, outcomes, study design criteria are listed in Table Two investigators (ZA and SD) independently extracted the following information from each qualified study: first author, year of publication, study design, country, age range/mean age, gender, sample size, diet assessment tool, the number of subjects with abnormal CMRFs/the number of subjects with CMDs, follow-up duration, exposure variable (DII/E-DII), and the number of food items used to calculate it, the type and definition of outcome, outcome assessment method, the type of DII score variable , and effect size, study quality, and confounders. Any disagreements were removed by the third author (MQ). Studies which reported correlation or beta coefficient, were included in the systematic review and they were not entered the meta-analyses.The quality assessment of included studies was performed by two independent reviewer using Newcastle–Ottawa Scale (NOS) . This scAll observational studies with any reported effect size (odds ratio (OR), hazard ratio (HR), correlation, or Beta coefficient) were included in qualitative synthesis. Meta-analysis was performed only for studies which reported OR and HR.In meta-analysis, we examined association of all types of DII  with CMRFs and CMDs. Meta-analyses were performed separately for CMRFs morbidity, CMDs morbidity, and CMDs related mortality.I2 [I2 > 50% and p < 0.1 for the result of Q test. If the results showed the heterogeneity, a random-effects model (the DerSimonian–Laird estimator) was applied to assess the pooled OR/HR. The results of the meta-analyses were schematically presented by forest plots.We performed random/fixed effects meta-analysis using maximally adjusted OR/HR with 95% confidence interval (CI). Heterogeneity among studies was assessed by I2 –39. TherDose–response meta-analysis was performed using a method suggested by Greenland and Orsini  to assesPublication bias was examined using Egger test and funnel plots. Subgroup analysis according to the type of study design was used to examine the association between the DII score with risk of CMDs and mortality. Sensitivity analysis was performed to assess the effect of removing any of the studies or group of studies on CMDs and CMRFs. All statistical analyses were performed using Stata software version 12  and p-value < 0.05 was considered statistically significant.A flow diagram for the process of study selection is shown in Fig. Overall, 55 eligible publications were included in the study. Tables The positive association between the DII score (as a continuous variable) and risk of CMDs and mortality was observed in three , 19, 57 The DII score  was associated significantly with the risk of CMDs in six studies , 53, 57 Totally, 39 studies  , 73–79, Thirteen studies that investigated the association between the DII score (as a continuous variable) and risk of CMDs and mortality were included in this meta-analysis , 78, 79 We also assessed the association between the categorical DII score and risk of CMDs and mortality using 18 observational studies , 77–79. Also, the association between the DII and risk of CMDs was statistically significant in cohort  and non-cohort studies   included in the meta-analysis , 73, 76 nonlinearity < 0.001). Unlike the overall association, the DII score was inversely associated with CMDs mortality from score of − 5 to − 2 (Pnonlinearity = 0.01). However, the risk was significantly increased when increasing the score of DII from − 2 to 1.5 (Pnonlinearity < 0.001). The slope was slightly flattening from DII score of 1.5 to upper levels  . Moreover, the results of Egger test for studies evaluated the association between the continuous DII score and risk of CMDs and mortality showed that there was no evidence of publication bias between studies   on risk of CMDs and mortality. In terms of MetS and its components, the results of sensitivity analysis demonstrated that neither an individual study nor group of studies had a remarkable effect on our results.The present meta-analysis showed evidences of the association between increasing the inflammatory potential of diet and risk of CMDs and mortality. Also, individuals with the highest pro-inflammatory diet had 13%, 21%, and 17% higher risk for MetS, hyperglycemia and HTN than those with the lowest pro-inflammatory diet.Subgroup analysis showed that the association of DII  with risk of CMDs did not change appreciably in the cohort and non-cohort studies. One important issue in studies on the association of the dietary indices and chronic diseases is the sample size. We can find more precise results using larger sample sizes. Similar findings in the cohort and non-cohort studies can be probably explained by the larger sample size of non-cohort studies.In the current study, there was a significant association between the DII score and risk of CMDs and mortality. There are some theories that explain the relationship between the DII score and risk of CVDs. Findings of studies showed that higher consumption of pro-inflammatory foods such as red and processed meat, sugar, and refined grains increases level of IL-6, TNF-a, and hs-CRP . Higher A population-based study including 1,363 men aged 18 years and older (the Geelong osteoporosis study) showed that the adjusted OR (95% CI) for CVDs was 2 (1.01–3.96) for those with pro-inflammatory diet compared with anti-inflammatory diet . The PREThis meta-analysis of 16 studies examining the association between the DII score and MetS or at least one of its components , 73, 76,The meta-analysis of 14 studies revealed that subjects in the highest versus the lowest DII score category showed 36% increased risk of CVDs incidence and mortality . AnotherThe current study had several limitations. Absence of a specific cut-off point for the association of the DII score and occurrence of morbidity or mortality of CMDs is the first limitation. Most of studies included in the MetS and its components analyses had a cross-sectional design, so the limitations of this type of study should be considered and the results should be interpreted with cautious. Other limitations include different numbers of dietary factors used in the DII score calculation and applying different adjustment models in the analyses. Evidence of publication bias, the other limitation, was observed when the DII score was considered as a categorical variable in the analyses.The current meta-analysis study showed a positive association between the DII score and risk of CMDs and mortality. Also, we find a significant association between adherence to pro-inflammatory diet and MetS, hyperglycemia, and HTN. More studies with prospective designs and in different societies are needed to confirm the findings.Additional file 1: Appendix S1. PRISMA 2009 Checklist.Additional file 2: Table S1. Search strategy in PubMed.Additional file 3: Figure S1. Dose–response association between the DII and risk of cardiometabolic diseases mortality.Additional file 4: Figure S2. Dose–response association between the DII and risk of cardiometabolic diseases.Additional file 5: Figure S3. Dose–response association between the DII and risk of cardiometabolic diseases in cohort studies.Additional file 6: Figure S4. Funnel plot of dietary inflammatory index (DII) (as a continuous variable) with risk of cardiometabolic diseases.Additional file 7: Figure S5. Funnel plot of dietary inflammatory index (DII) (as a continuous variable) with risk of cardiometabolic diseases mortality.Additional file 8: Figure S6. Funnel plot of dietary inflammatory index (DII)  with risk of cardiometabolic diseases.Additional file 9: Figure S7. Funnel plot of dietary inflammatory index (DII)  with risk of cardiometabolic diseases mortality.


To carry out the meta-analysis on the relationship between the expression of nucleotide excision repair cross-complementary enzyme 1 (ERCC1) protein and platinum chemosensitivity in patients with advanced non-small-cell lung cancer (NSCLC).  The literature on the expression of ERCC1 and platinum chemosensitivity in patients with advanced NSCLC was searched in computer, which was published from January 2009 to August 2019 on the databases such as China Journal Full-text Database (CJFD), China National Knowledge Infrastructure (CNKI), Wanfang Database, VIP, PubMed, EMBASE, and others. Stata 15.0 was used for statistical analysis, and ethnicity subgroup analysis was taken. P < 0.01). The results of ethnicity subgroup analysis showed that there was no significant difference, with OR of 0.50  in Asian population and OR of 0.56 (95% CI: 0.30∼1.07) in Caucasian population.  Finally, 14 studies were included and 1337 patients were involved, of which 697 were ERCC1 positive, with a positive rate of 53.5%. The combined OR was 0.53 (95% CI: 0.30∼0.79;  The sensitivity to platinum chemotherapy in patients with ERCC1 protein negative expression in the middle and late stages of NSCLC is better than that in patients with positive expression, especially in Asian population. There is no correlation in Caucasian population. Lung cancer is one of the most common malignant tumors at present, and the number of patients with which is increasing rapidly all over the world. It has the highest mortality rate in the world, with the annual deaths of more than 1 million , 3, amonWith the keywords of lung cancer, ERCC1, and platinum, the literature from January 2009 to August 2019 was searched in the databases such as CJFD, CNKI, Wanfang Database, VIP, PubMed, and EMBASE. The preliminary screening was done mainly by reading the abstracts. And then the references of the literature that met the inclusion criteria were carefully read to get the wanted articles. The selected literature was published in Chinese or English.(1) The subjects were patients with advanced NSCLC, that is, patients at clinical stages II–IV. (2) The case-control study on the expression of ERCC1 protein and efficacy of NSCLC in platinum chemotherapy was analyzed. (3) NSCLC was primary lung cancer and diagnosed by pathology or cytology. (4) The test method of the protein expression of ERCC1 was immunohistochemical (IHC) staining. (5) The WHO standard was used as the evaluation standard of curative effect, with the complete remission + partial mitigation as the total effective rate. (6) For the multiple reports of the same author, the latest or most complete reports were used. (7) The Chinese literature was those included in the Core Database of Peking University Library.(1) The study was on animal experiment or the lung cancer cell line. (2) The study was on the nonprimary lung cancer, such as metastatic or recurrent cancer. (3) The study was on the SCLC. (4) The study was about chemotherapy with nonplatinum regimen, with less than 2 courses of chemotherapy. (5) The study was on the relationship between the expression of ERCC1 protein and the efficacy of platinum chemotherapy, such as ERCC1 mRNA and ERCC1 gene polymorphism.All the following information was extracted from the included literature: (1) general information: it includes researchers, publication time, and the country; (2) the literature characteristics: clinical staging, chemotherapy regimen, the number of ERCC1-positive and ERCC1-negative cases, and the number of effective cases of chemotherapy; and (3) methodological features: it includes ERCC1 detecting methods, cutoff value, statistical methods, and results. As the inclusion of the literature is retrospective studies, there are no random and blind requirements. The quality of the literature was evaluated according to the Newcastle–Ottawa Scale (NOS) , with loQ test was used to test the heterogeneity of the results. If I2 ≥ 50% or P ≤ 0.05, it is considered that there was heterogeneity, and the random-effects model was used. If I2 < 50% and P > 0.05, it was considered that there was no heterogeneity, and the fixed-effects model could be used for data consolidation. Z test was used to test the significance of the combined OR value. In this meta-analysis, the evaluation of publication bias of the included literature was judged by whether the funnel plot was symmetrical or not. Funnel plot was to use the standard error of each study log (OR) to draw its OR value. If the funnel plot was asymmetric, there may be publication bias. Egger's test and Begg's test were used to test the publication bias.The meta-analysis was carried out by Stata 15.0 software. The OR and 95% CI, as the effect size, were calculated to represent the results. The databases were searched comprehensively, and then, the retrieval results were cross-checked. The selected literature was screened in strict accordance with the exclusion criteria and the quality control requirements after reading carefully. At the end, 14 articles –28 were P ≤ 0.001; I2 = 61.2%). Using the random-effect model to analysis, the forest plot was obtained, which is shown in P < 0.01). The results of ethnicity subgroup analysis showed that, for Asian population, there was a significant difference with the combined OR of 0.50 . For Caucasian population, with the combined OR of 0.56 (95% CI: 0.30∼1.07), the difference was not statistically significant, as shown in P < 0.05). This showed that tumor staging was one of the sources of heterogeneity.The meta-analysis of the included 14 studies showed that there was statistical heterogeneity among the studies , the enhancement of DRC, and the increase of platinum-DNA adducts . BesidesP value is slightly less than 0.05, so there is a partial publication bias. Each study is excluded one by one, and meta-analysis is used. Then, the sensitivity analysis shows that there is no significant change in the combined effect, indicating that the stability of the included study is good. It can be seen that the conclusion drawn from the study is relatively reliable. However, considering that there are few studies on Caucasian population, and their OR values are low, with the upper limit of 95% confidence interval only slightly greater than 1. Therefore, the conclusion of Caucasian population still needs to be treated with caution. The study of Dong et al. [The meta-analysis includes 14 articles –28, consg et al.  on the eOf course, this study also has some limitations: (1) The methods used in the included literature are basically IHC. When it is used to detect the expression of ERCC1, there are differences in the scoring criteria among the studies. (2) The scope of the selected research is narrow, mostly in Asian countries, only 9 in Europe and America, but none in Africa and other countries. (3) Although IHC is used to detect the expression of ERCC1 in all of the studies, the manufacturer, dilution concentration, and judgment criteria of antibody are not completely consistent, which may affect the results of meta-analysis. (4) The test of publication bias on the overall study and the population in Asian countries shows that there is still a partial publication bias. However, these results should be interpreted with caution, as the criteria for judging gene expression are inconsistent in the selected studies. Sensitivity tests may also be necessary. In addition, prospective studies with larger sample sizes still need to further confirm these findings.In conclusion, there is a correlation between the high expression of ERCC1 and the chemosensitivity of NSCLC platinum drugs. The low expression of ERCC1 is more sensitive to platinum chemotherapy in patients with advanced NSCLC, especially in Asian population, but not in Caucasians. The state of ERCC1 may be a potential biomarker for predicting the efficacy of platinum chemotherapy in NSCLC. However, considering the limitations of this study, large-scale and well-designed studies are still needed to investigate the factors that may affect the response to platinum chemotherapy.


Supplemental Digital Content is available in the text Studies on the relationship between ABCB1 3435C>T polymorphism (rs1045642) and colorectal cancer (CRC)susceptibility have yielded inconclusive results. To clarify this issue, we undertook a meta-analysis to investigate the relationship between rs1045642 and CRC risk.Three electronic scientific publication databases  were screened using specific search terms. Relevant literature was identified using literature traceability methods. Selected publications were evaluated according to the inclusion and exclusion criteria. Effect size information  was obtained following quality assessment and data extraction from the included publications, and a meta-analysis conducted. Statistical analysis was performed with the Stata sofz (Version 13.0) software.I2 = 20.9%, Pheterogeneity = .276), CC versus CT + TT model  and CT versus CC + TT model  analyses, between-study heterogeneities were detected as significant in Asian populations. In the CT versus TT model  and CC + CT versus TT model , between-study heterogeneities were found to be significant in groups of different populations.Overall, 17 case-control studies involving 7129 CRC patients and 7710 healthy control subjects satisfied the criteria for inclusion in the meta-analysis. There was no significant association between ABCB1 3435C>T polymorphism and CRC risk in any of the genetic models. In the CC versus CT model (The meta-analysis described here suggests that the ABCB1 3435C>T polymorphism is not related to CRC susceptibility. Lifestyle difference is also a vital factor leading to the striking variation in CRC morbidity globally. Differences in access to prevention, the quality of treatment technology, and the economic level of the patients greatly affect the mortality rate of CRC patients. Although the incidence of CRC in the United States has been tapering off in recent years, worldwide, the outlook does not give grounds for optimism.,5,6In a global context, colorectal cancer (CRC) represents a serious threat to human life and health. What is more, it confers an enormous economic burden on society. CRC is the third most commonly diagnosed cancer in the United States. Its estimated morbidity and mortality incidence will be the third among all carcinomas in the United States in 2019. P-gp mediates multiple drug resistance in cancer cells through various signaling pathways, such as the cyclic adenosine monophosphate/protein kinase A pathway,,9 the phosphatidylinositol 3-kinase/protein kinase B pathway,–12 the Y-box binding protein 1,,14 the phosphatase and tensin homolog,,16 p53, protein kinase C, and other protein kinases. Previous studies have shown that ABCB1 is overexpressed in a variety of tumors, such as breast cancer, acute myeloid leukemia, hematological malignancies, childhood tumors, and other solid tumors.The adenosine triphosphate-binding cassette subfamily B member 1 (ABCB1) gene, also known as multidrug resistance gene 1 (MDR1), is located on the chromosomal region 7q21.1 and encodes the P-glycoprotein (P-gp). P-gp is a 1280-amino acid transporter that serves as a genetically polymorphic efflux transporter that removes foreign substances from cells. Up to now, numerous SNPs, including some synonymous ones, have been identified in the coding region. Three SNPs in the coding sequence  are the most widely studied in ABCB1; these are relevant to the substrate and inhibitor-dependent functional modifications observed in vitro and reduced expression in tissues. The distributions of rs1128503, rs1045642, and rs2032582 differ significantly among races and ethnicities. It is reported that Africans and African-Americans harbor the lowest frequencies of polymorphic alleles and Asians and Caucasians possess the highest.Single nucleotide polymorphisms (SNPs) of ABCB1 affect its expression and function. So far, numerous epidemiological studies have been performed to assess the association between rs1045642 and risk for CRC. However, due to the limitations of individual studies, the results are inconsistent. To help resolve this matter, we performed a meta-analysis based on a total of 17 independent studies, to obtain a more precise estimation of the association between rs1045642 and the risk of CRC. This meta-analysis suggested ABCB1 3435C>T polymorphism is not related to CRC susceptibility.The ABCB1 3435C>T polymorphism is a synonymous SNP with no impact on the structural contribution of the amino acid at position 1145 (Ile) in the second ATP binding domain but does affect the expression of P-gp in tissues.22.1We queried the Cochrane Library, Pubmed, and Embase databases on August 1, 2019. Keyword combinations for colorectal neoplasms  or colonic neoplasms  and gene symbols, and synonyms for the ABCB1 gene  and polymorphism  were used to form a Boolean query formula. Two reviewers (L.H. and Z.Z.), independently and in duplicate, screened titles and abstracts using a standardized data form tested in pilot runs. Inconsistencies regarding inclusion were resolved through consensus. The meta-analysis did not involve data related to patient personal information and therefore does not require ethical approval.2.2The criteria for inclusion in the study were as follows:(1)manuscripts from peer-reviewed journals;(2)case-control studies assessing the association between the ABCB1 3435C>T polymorphism (rs1045642) and CRC;(3)studies focusing on CRC or colonic cancer;(4)no inconsistencies in genotype data for either cases or controls; and(5)studies with enough genotype data to estimate the odds ratio (OR) and 95% confidence interval (CI) in at least one genetic comparison model.The exclusion criteria were:(1)not case-control studies,(2)control population including malignant tumor patients, and(3)duplicate publications.Two individual authors (L.H. and Z.Z.) performed the literature selection process. Another author (B.Z.) performed an investigation to reach an eventual agreement if the first 2 reviewers came to contradictory conclusions.2.3Two investigators reviewed and extracted information from all qualified publications based on the inclusion and exclusion criteria listed above. When there was a conflict, the 2 reviewers reached an agreement through discussion. The following information was extracted from each included study: first author's surname, year of publication, ethnicity, total numbers of cases and controls, as well as numbers of cases and controls with CC, CT, and TT genotypes. Individuals of different descent were categorized as Caucasian and Asian. Individuals of different descent were categorized as Caucasian and Asian.2.4 Studies were scored according to TSQA standards (Supplementary Table S1). Studies of high quality were given scores of greater than 9.The quality of the included studies was evaluated by the total score of quality assessment (TSQA).2.5Q test was used to test the heterogeneity assumption. A value of P < .1 in the Q test indicated that the between-study heterogeneity was significant. However, when P≥.1, the pooled ORs and 95% CIs should be measured using a fixed-effect model employing the Mantel–Haenszel algorithm. To explore the effect of heterogeneity among the studies on the conclusions of this meta-analysis, we performed subgroup analyses by ethnicity. We examined the ABCB1 3435C>T genotypes using dominant (CC + CT vs TT), recessive (CC vs CT + TT), and overdominant (CT vs CC + TT) genetic models, as well as the allelic model (C vs T). The estimated OR and 95% CI were obtained from Forest plots. Publication bias was graphically detected by funnel plots. The symmetry of the funnel plot was further evaluated by Egger linear regression test. The significance of the intercept was determined by the t test suggested by Egger, where P < .05 was considered representative of statistically significant publication bias.The measure of effect in these studies was the OR with 95% CI. Summary measures were pooled using random-effects models, with the estimate of heterogeneity taken from the Mantel-Haenszel model. All statistical analyses were conducted in the Stata 13 environment. The aggregated estimate of the OR and corresponding 95% CI were calculated for the dominant model , the recessive model (CC vs CT + TT), and the overdominant model (CT vs CC + TT). Cochran's Chi-square-based 33.1–42 In total, 7,179 CRC cases and 7,710 controls were included in the meta-analysis. The characteristics of the selected studies are summarized in Table From the searches for studies on colorectal neoplasms or colonic neoplasms and C3435T genotypes, 153 potentially eligible records were identified. Titles and abstracts of these records were screened for inclusion. Seventeen independent studies met the inclusion criteria, consisting of six Asian and eleven Caucasian populations , CC versus CT + TT model , and CT versus CC + TT model , between-study heterogeneities were determined to be significant  and CC + CT versus TT model , between-study heterogeneities were found not to be significant  group), while in six studies the participants were 4541 patients with CRC and 4798 healthy individuals who were selected from the general population (population-based (PB) group). All genetic models were evaluated using the random-effect statistical model. For the PB group, the striking between-study heterogeneities were minimized. For all genetic models except for the CT versus TT model .3.6P values for Begg funnel plot were .201, .57, and .104, respectively, indicating that there was no significant publication bias  for its linguistic assistance during the preparation of this manuscript.This work was supported by the National Natural Science Foundation of China (81903031), Zhoukou Normal University Guiding Project (ZKNUC2018011). We thank LetPub (Guo-yin Li designed the study and drafted the initial manuscript. Li-li Han, Bai-le Zuo and Wei-liang Cai contributed to initial data analysis and interpretation. Zhen-ni Guo, Bing-hua Tong and contributed to the production of the pictures. Guo-yin Li and Zheng zhu supervised all aspects of the study, critically reviewed and revised the manuscript, and approved the final manuscript as submitted.


MTHFR, may control blood pressure in patients with mutant MTHFR variants. These double benefits of a risk stratification tool and treatment approach make it interesting. Because this polymorphism depends on ethnicity and geographic region, we aimed to determine the association between MTHFR C677T gene polymorphism and hypertension in a rural Indonesian-Sundanese population. This population-based case-control study included 213 hypertensive subjects and 202 nonhypertensive subjects as controls. The TaqMan assay was used to determine the MTHFR C677T genotypes. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the risk of association. There was a significant difference in MTHFR C677T allele frequencies between the hypertensive and control groups  and between mutant (TT and CT) and wild-type genotypes (CC) (p=0.001). The mutant genotype was associated with a risk of hypertension  when adjusted for age, body mass index, waist circumference, and diabetes mellitus. The mutant of the MTHFR C677T gene increases the risk of hypertension in rural Indonesian-Sundanese population. These findings may be used in future studies to evaluate the effect of riboflavin supplementation in this population.Hypertension remains a public health burden despite advances in its management. Hence, the search for further risk stratification tools and prevention and new treatment approaches continues. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with hypertension. Interestingly, riboflavin, as a cofactor of  MTHFR C677T gene from alanine to valine reduces enzymatic activity, which, in turn, decreases the concentration of 5-methyltetrahydrofolate, which regulates the endothelial cells and nitrite oxides (NO) involved in the pathophysiology of hypertension  if the data are nonnormally distributed. The chi-square test or Fisher's exact test was used for categorical data, and the unpaired t-test or Mann–Whitney U test was used for continuous data. The odds ratio (OR) and 95% confidence interval (CI) were calculated to estimate the association between various MTHFR genotypes and hypertension risk factors using the logistic regression test. A p value <0.05 was considered statistically significant. The chi-square test and Fisher's exact test were performed to test the Hardy–Weinberg equilibrium among each population surveyed, and the differences among the populations were compared with respect to allele and genotype frequencies.Data analysis was performed using SPSS version 23 . Categorical data are presented as number . Gender was distributed equally in both groups, with female predominance.Cases had a higher rate of obesity than controls. Central obesity was also higher in cases than controls. No significant difference in smoking status between groups was observed. Cases had a higher number of diabetes mellitus than controls, but the difference was not statistically significant .p > 0.05. In controls, Fisher's exact test was performed with p=0.87. Hence, further analysis could be performed because the genotypes were in concordance with the Hardy–Weinberg equilibrium. Examples on how to assess the genotype are shown in Figures The Hardy–Weinberg equilibrium test was performed to analyze the genotype distribution. In cases, the chi-square test was performed with The genotype and allele frequency between groups was significantly different, with more mutant frequency observed in cases than controls .MTHFR polymorphism were included in the multivariate analysis using the double logistic regression test. In the first stage, diabetes was excluded because its p value was 0.7, with 95% CI of 0.4–3.3. The final model of multivariate analysis is presented in MTHFR C677T, age, BMI, and waist circumference. Polymorphism of MTHFR C677T significantly increased the risk of hypertension up to 2.1 times; BMI increased the risk of hypertension by 4.7 times; and waist circumference was related to hypertension. Meanwhile, age was found to be protective.After conducting bivariate analysis, age, BMI, waist circumference, diabetes mellitus, and MTHFR C677T polymorphism with hypertension in Indonesia, especially in a rural Sundanese population. The major finding of this study was that the presence of MTHFR variants was an independent predictor of hypertension.To the best of our knowledge, this is the first study to investigate the association between MTHFR C677T polymorphism is an interesting subject because of its advantage as a risk stratification tool and its potential for therapeutic intervention [Hypertension is influenced by genetic and environmental factors. The rvention , 14, 15.This case-control study was performed as a population-based study, which offers many advantages because of the homogeneity of the geographic region, ethnicity, and lifestyle similarities . These mFrom this study, we found that the CC genotype had the highest proportion in cases (62.9%), followed by CT (34.3%) and TT (2.8%). Although the mutant genotype frequency was high (37.1%) in this study, the homozygote mutant TT showed only 2.8%. This low proportion could be caused by recurrent early pregnancy loss (REPL), which prevented the survival of fetuses with the TT genotype. Several studies linked this gene polymorphism with REPL incidence up to 2–3 times through hyperhomocysteinemia and the absence of vitamin B-based supplementation –20. TherMTHFR C677T was associated with increased risk of hypertension . This finding was similar to that of the study conducted by Wu et al. [After adjustment for age, BMI, waist circumference, and diabetes mellitus, we found that The genotyping method used in this study was the TaqMan assay, which was reported to have better sensitivity and accuracy than those of restriction fragment length polymorphism. This study was also in concordance with the Hardy-Weinberg equilibrium, which indicated that both groups had a homogenous population, less tendency to have genotyping error, proper random sampling, and adequate sample size .In this study, diabetes mellitus status was established based on the memory of the subject of a history of confirmed diagnosis or treatment. Hence, the lack of laboratory confirmation was the limitation of this study.In a study conducted by Horigan et al. , riboflaMTHFR C677T is associated with an increased risk of hypertension. This study shows the need for risk stratification and investigations into the potential preventive and therapeutic effect of riboflavin, either for personalized medicine or a community approach.Polymorphism of


We aimed to assess the effect of a high-quality diet on the risk of upper gastrointestinal cancer and to evaluate the overall quality of our findings by searching PubMed, EMBASE, Web of Science, Cochrane, and the references of related articles to February 2020. Two reviewers independently retrieved the data and performed the quality assessments. We defined the highest-quality diet as that with the lowest Diet Inflammatory Index category and the highest Mediterranean Diet Score category. Overall odds ratios and 95% confidence intervals were estimated for upper gastrointestinal cancer risk comparing the highest- versus lowest-diet quality. A random-effects meta-analysis was then applied with Review Manager, and the quality of the overall findings was evaluated with the Grading of Recommendations Assessment, Development, and Evaluation approach. The highest-quality diets were significantly associated with reduced risk of upper gastrointestinal cancers, achieving odds ratios of 0.59  for the Diet Inflammatory Index, pooling the findings from nine studies, and 0.72  for the Mediterranean Diet Score, pooling the findings from 11 studies. We observed a minimum of 69% heterogeneity in the pooled results. The pooled results were graded as low quality of evidence. Although it may be possible to offer evidence-based general dietary advice for the prevention of upper gastrointestinal cancers, the evidence is currently of insufficient quality to develop dietary recommendations. Upper gastrointestinal (UGI) cancers, including those of the stomach, esophagus, and nasopharynx, are a leading cause of morbidity and mortality worldwide, accounting for some 1.6 million new cases and 1.3 million deaths each year .,3,4.2,3,Variations in the methods, such as the study design, the geographic region, the study population, the method of quantifying diet quality, and the anatomical tumor site are considered to account for the existing discrepancies, resulting in inconsistency in meta-analyses. This problem has been compounded by the lack of analysis of the overall quality of existing data, and together, these have prevented the development of meaningful dietary recommendations for the prevention of UGI cancer ,14,15,16In this text, we report a systematic review and meta-analysis with two aims. First, we assessed the effect on UGI cancer risk of diet quality measured by diet indices. Second, we aimed to study whether the existing evidence on the beneficiary role of diet quality in the prevention of UGI cancer could be translated into evidence-based dietary recommendations for the prevention of UGI cancers.We formulated the search strategy for PubMed, Embase, Web of Science, and Cochrane with the assistance of a medical librarian . The strWe included studies measuring diet quality with a diet index as part of their a priori design. In these, UGI cancer cases were required to be identified by the presence of one or more of following: self-report questionnaire or pathology records reviewed by a trained physician, linkage to a cancer registry system, or linkage with a mortality records system.SM and KWJS extracted the following information: study design, first author, publication year, study country, applied diet index, number of included food components, gender, and age (mean or range). The total population size and incident cases were recorded for cohort studies, and the number of cases and controls were recorded for case-control studies. They also recorded the number of adjusting variables, the outcomes, and the most adjusted risk estimates with corresponding 95% confidence intervals (CIs) comparing the highest and lowest diet index categories.Finally, study quality of eligible studies was appraised by the Newcastle–Ottawa quality assessment scale, according to three parameters: selection, comparability, and exposure for cohort and case-control studies as the following .Selection. The representativeness of the exposed and unexposed populations, and the adequacy of outcome demonstration; (ii.) comparability. Control for age, gender, and at least three additional risk factors, including body mass index, ethnicity, family history of gastrointestinal (GI) cancers, smoking, alcohol, physical activity, dietary supplement intake, helicobacter pylori, and gastroesophageal reflux disease (GERD); (iii.) Exposure/outcome. The methods used for outcome assessment, the adequacy of outcome follow-up , and the details of any loss to follow-up; for case-control studies, the selection and exposure parameters were modified, as follows (i.) selection. The adequacy and representativeness of the case definition, the control selection , and the confirmation of no history of GI cancer among controls; (ii.) exposure. Whether the same methods were applied to cases and controls for exposure assessment . As for cohort studies, the following items were evaluated as (i.) Eventually, study quality was ranked as low (≤3 stars), moderate (4–6 stars), or high (≥7 stars). The maximum scores allocated for study quality were nine stars for a cohort study and eight stars for a case-control study. Any disagreements were resolved by discussion and mutual agreement.When there were less than three studies for a certain diet quality measurement, studies were not pooled, as in this situation, the grading of the quality of overall findings is limited. Therefore, in a quantitative meta-analysis, diet quality indices, which were investigated in three or more studies, were included. Hence, we included DII and MDS in the analyses. For the DII, we used the most adjusted risk estimates for the lowest compared to the highest category , while tonducted . The sta2 was ≤25% (indicating low heterogeneity), in which case we applied fixed-effects models. The pooled results for the DII and MDS were determined by the inverse variance method. For the sensitivity analysis, we assessed the consistency in the pooled results by excluding one study at a time and recalculating the pooled effect at each step. We also conducted stratified analyses to check the consistency of the findings within strata and to explore potential sources of heterogeneity by geographical region , gender , and tumor site . Analyses were conducted using Review Manager, Version 5.3  and Comprehensive Meta-Analysis software, version 2.2 .The natural logarithms of the ORs, together with their SEs and corresponding CIs, were calculated later. Publication bias was assessed by visual evaluation of funnel plots and Egger’s regression tests for funnel plot asymmetry. To handle the publication bias, we applied the trim and fill methods, as proposed by Duval and Tweedie . In thisTo evaluate whether the existing evidence is of sufficient quality in developing evidence-based dietary recommendations for the prevention of UGI cancers, we evaluated the quality of the pooled results on the risk of UGI cancer for both the DII and MDS, using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach . The proWe obtained the required information on cancer incidence rates for the country of corresponding studies within the follow-up period, using the databases offered by the website of Global Cancer Observatory. This web-based platform presents worldwide cancer statistics to provide information both for cancer research and cancer control. The data on global epidemiological profile of cancers are supplied by several projects of the International Agency for Research on Cancer, including GLOBOCAN, Cancer incidence in five continents, and cancer survival; in Africa, Asia, the Caribbean, and Central America. The required information on applied methodology in this systematic review and pooling the findings, and quality assessment of overall findings were obtained from the Cochrane handbook and website ,20.Of the 53 studies retrieved for full-text review, 24 met the selection criteria . UGI canp = 0.26).We included two cohort studies ,8 and seLow DII scores did indicate statistically significant protection against UGI cancer, with a pooled OR of 0.59 (95% CI: 0.48–0.72). The heterogeneity remained significant after excluding studies with extreme findings, identified by funnel plot asymmetry ,27 or reThe direction of the pooled effects by gender was not consistent with the overall effect , and hetThe pooled results were scored −2 when grading the overall evidence level. This was because the findings were limited to Europe and Asia (scoring −1) and were inconsistent (scoring −1) .p = 0.01) . However, after excluding studies with extreme findings [We included five cohort studies ,7,10,11  = 0.01) . Findingfindings ,35, the The quality of evidence was given a score of −3 due to the findings being restricted to specific geographic regions, such as Europe (scoring −1), the lack of consistency (scoring −1), and the possibility of publication bias (scoring −1) .In this systematic review and meta-analysis of 21 studies, which included a total of 1,558,724 individuals, we showed that a high-quality diet quantified by the DII and MDS was significantly associated with a reduced risk of UGI cancer. However, the data suffered a few limitations. The overall beneficial effect was not consistent for diet quality measured by the DII when stratified by gender. In addition, a high-quality diet measured by the MDS was significantly and consistently associated with a lower risk of UGI cancer when stratified by gender and tumor site. The overall quality of the evidence was graded as low regarding the beneficial effect on UGI cancer risk for a high-quality diet measured by dietary indices.The overall beneficial effect of a high-quality diet measured by the DII was consistent with that of a recent meta-analysis pooling the findings of three case-control studies and reporting a 2.11-times reduction in the risk of gastric cancer . By contIn our current meta-analysis, two studies presented extreme findings compared with the pooled results ,29. The Based on the results of this meta-analysis, gender may be considered a key factor contributing to high overall levels of inconsistency. However, other factors also appeared to contribute to inconsistencies in pooled results. These included substantial inter-tumor heterogeneity in UGI cancers and adjustment for different covariates, as well as variability in the dietary component of the DII, the categories applied for analysis with the DII, and the methods used to validate the food frequency questionnaires. The low quality of the overall findings, mainly due to the observed inconsistency and indirectness (limited studies from Asia and no evidence for North America), reduced our confidence in the observed benefit of a low DII score being associated with reduced UGI cancer risk. Similarly, the diversity in the scoring system based on the inflammatory response of food components (ranging from 18 to 45 food components) and the low transparency hamper the ability to generate dietary recommendations for preventing UGI cancers based on the DII scoring system. Thus, further research is required using a consistent scoring system for the DII, especially in the less-well represented areas, if we are to draw robust conclusions about applying the related evidence to generate dietary guidelines for the prevention of UGI cancer.The benefit of an MDS-based high-quality diet for preventing UGI cancer agreed with the conclusions of a recent meta-analysis that included four of the eleven studies in our meta-analysis. Despite the overall beneficial findings in the present analysis, however, we found no beneficial effect in the four included studies ,6,7,12. The inconsistency in the findings by geographic region confirms that study region can explain much of the overall discrepancy in the results. In the current meta-analysis, our findings were mostly restricted to Europe, necessitating investigation in other geographic areas to confirm or refute whether the geographic region is responsible for the observed inconstancies. Our data do, however, support excluding gender and tumor type as causes of heterogeneity, based on the observation that benefits persisted in these strata. Thus, factors such as inter-tumoral heterogeneity and differences in the covariates adjusted for in the included studies may remain potential sources of heterogeneity. Accordingly, research must confirm the generalizability of high adherence to the MDS for preventing UGI cancer.The low overall quality of our findings, mainly due to inconsistency and a lack of data for North America and Asia, precludes developing global dietary recommendations for the prevention of UGI cancer. Nonetheless, the high consistency in the findings of prospective research highlights the high quality of the evidence for general dietary recommendations to prevent UGI cancer. Overall, prospective investigations with broader scope are warranted to compensate for the limited evidence from underrepresented regions. In turn, it is anticipated that this will aid the development of global dietary guidelines for the prevention of UGI cancer.Findings from investigations quantifying diet quality based on Chinese Healthy Food Patterns , DietaryThis research benefitted from an extensive assessment of the role of diet quality, measured by commonly applied dietary indices, on the risk for UGI cancer. Specifically, we applied robust grading of the overall quality of our findings. We provided a comprehensive overview of the repercussion of existing evidence for developing dietary recommendations to prevent UGI cancer. Nevertheless, the pooled findings were inevitably affected by the limitations inherited from the included observational studies, despite rating overall quality. In these observational studies, difficulties exist in a person’s habitual diet assessment. First, dietary assessment is dependent on the memory of the study subjects. Second, dietary assessments are prone to possible recall biases in unconscious over-reporting of a healthy diet and under-reporting of an unhealthy diet and fluctuations in diet habits based on changes in the environmental and lifestyle situations. This, in turn, leads to an imbalanced recall among participants.Furthermore, diet quality assessment has mostly been done by a single dietary intake assessment, while dietary habits change over time. Accordingly, while multiple dietary assessments over time would represent more precise actual dietary habits, a single dietary assessment may fail to provide a real reflection of dietary habits. Among other limitations of this study is the substantial heterogeneity in pooled results for the DII and MDS, necessitating that we conduct extensive stratified analyses of the main confounding factors . Another shortcoming is that the findings were mostly restricted to a specific geographic region; consequently, the results cannot be generalized. The overall quality of the findings for both indices was, therefore, downgraded.Although our findings suggest a possibility to offer evidence-based general dietary advice for the prevention of UGI cancer, the evidence is currently of insufficient quality to develop dietary recommendations. Developing a dietary recommendation for UGI prevention will provide a unified approach that could be clinically applied to improve the diet quality of people at higher risk of UGI cancers, leading to better prevention, and can also be used as a mandate to improve the quality of diet in patients already diagnosed with UGI cancers which, in turn, may lead to a better prognosis.