there has been an increase of prevalence of obesity which is associated with several adverse health problems , including type 2 diabetes , hyperlipidemia and hypertension . the role obesity plays in the development of obesity - related disorders is complex and probably due to an interaction of genetic , nutritional and metabolic factors [ 1 , 2 ] . a number of candidate genes have been implicated in the pathogenesis of obesity in humans . tumor necrosis factor- ( tnf- ) is primarily secreted in adipocytes , and elevated levels of this cytokine have been linked to obesity and insulin resistance . tnf- messenger rna levels in skeletal muscle and adipose tissue of humans are positively correlated with body mass index ( bmi ) , fat mass , and insulinemia and inversely correlated with lipoprotein lipase activity [ 35 ] . the gene which is coded human tnf- is located on the short arm of chromosome 6 . recently , attention has been focused on two nucleotide polymorphisms identified in the promoter region of the tnf- gene : g    a substitutions at 308 and 238 respectively . in vitro experiments have demonstrated that the polymorphism 308 which is identified by ncoi restriction fragment length polymorphism ( rflp ) , increases transcriptional activation of the tnf- gene . the potential functional impact of the polymorphism at position 238 of the tnf- gene has not yet been investigated in in vitro expression studies . however , the variant is located within a putative y box , which is a regulatory motif typical of the promoter region of major histocompatibility complex class ii genes . the purpose of the present study is to determine whether the two mentioned tnf- promoter polymorphisms are associated with obesity in iranian population . subjects were randomly selected from cohort tehran lipid and glucose study and adults were classified in three groups according to their bmi : bmi  <  25 , 25    bmi  <  30 , bmi    30 . as for 308 polymorphism , 202 adults ( 81 men , 121 women ) and 42 under-18 subjects ( 21 boys , 21 girls ) were placed in two groups according to their bmi : under and above 85th percentile as far as age and sex are concerned . and as for 238 polymorphism , 239 ( 78 men , 120 women ) and 41 under-18 subjects ( 17 boys , 24 girls ) were classified in two groups according to their bmi : under and above 85th percentile as far as age and sex are concerned . bmi , waist to hip ratio , fat mass , and plasma concentration of glucose , serum levels of triglyceride , total cholesterol , and high - density lipoprotein ( hdl ) cholesterol were analyzed . in order to genotype the subjects , the standard salting - out proteinase k method was used to extract the germinal dna . both tnf- promoter polymorphisms were detected using the rflp method after amplification of the sequences by polymerase chain reaction ( pcr ) . a 107-bp fragment encompassing the 308 variant site was amplified from genomic dna by pcr using standard reagents , technique , and primers ( 5-agg caataggttttgaggggccat-3 ) and ( 5-tcctccctgctccgattccg-3 ) for the 308 variant and ( 5-atctggaggaagcggtagtg-3 ) and ( 5-agaagacccccctcggaacc-3 ) for the 238 variant allele . to detect 308 variant alleles the pcr product was digested with ncoi at 37c overnight , leaving a 107  bp fragment when the variant was present and products of 87 and 20  bp fragments for the normal allele visualized on 3% agarose gel . to detect the 238 variant alleles , the pcr product was digested with mspi at 37c for an hour , leaving a 152  bp fragment when the variant was present and products of 133 and 19  bp fragments for the normal allele visualized on 3% agarose gel . the mean levels of all normally - distributed variants were tested by anova and the mean levels of all abnormally - distributed variants were tested by nonparametric kruskal wallis h test and the data were presented as means    sd of the differences . the mean levels of all normally - distributed variants were tested by anova and the mean levels of all abnormally - distributed variants were tested by nonparametric kruskal wallis h test and the data were presented as means    sd of the differences . the distribution of tnf- genotype for 308 site in under-18 subjects was as follows : gg ( 81% ) , ga ( 16.6% ) , and aa ( 2.4% ) . in adults the following results were produced : gg ( 86.6% ) , ga ( 12.4% ) , and aa ( 1% ) . as for the 238 site in under-18 subjects the results were : gg ( 80.5% ) , ga ( 19.5% ) , and aa ( 0% ) , and in adults the following results were recorded : gg ( 79.3% ) , ga ( 19.2% ) , and aa ( 1.5% ) . clinical and biochemical data of participants , when classified in accordance to g / a polymorphisms at positions 308 and 238 of the tnf- gene promoter , are presented in table  1 ( 308 ) and table  2 ( 238 ) . to examine whether the variant alleles were more common in patients with obesity , adults were classified in three groups according to their bmi : bmi  <  25 , 25    bmi  <  30 , bmi    30 and under-18 subjects were classified in two groups according to their bmi : under 85th percentile bmi and above 85th percentile as far as age and sex are concerned table  3 ( 308 ) and table  4 ( 238).table  1clinical and biochemical data of subjects when classified in accordance to the genotype of the g / a polymorphisms at positions 308 of the tnf- gene promoterunder 18above 18traitgg ( 34)ga ( 7)aa ( 1)pgg ( 175)ga ( 25)aa ( 2)page ( years)12.51    2.814.21    2.2510.50.24043.34    15.6240.96    16.0451.25    1.760.591sex ( m / f)17/173/41/00.57270/10510/151/10.960bmi ( kg / m)19.73    3.8419.91    2.0726.710.17926.65    4.5527.33    4.8232.18    2.70.196fbs ( mg / dl)86.45    5.6287.35    6.5173.50.08889.00    22.1890.50    8.6687.5    7.070.865homa10.1    5.809.45 ( mg / dl)158.57    2.44169.79    22.38178.000.421196.57    42.73197.00    47.91208.75    44.900.925hdl - c ( mg / dl)44.30    8.6043    7.34290.20842.26    9.6342.76    9.2031.75    13.780.295ldl - c ( mg / dl)95.96    20.75109.69    22.87113.400.241124.53    3.46118.52    43.83128.75    40.090.723tg ( mg / dl)94.44 39.0085.85    21.80178.500.074128.50    81.07142.50    154.54241.25    44.190.053whr0.83    0.050.82    0.070.980.0530.87    0.080.86    0.090.95    0.060.344sbp ( mmhg)101.31    8.46104.21    5.12970.579114.50    17.26116.50    11.02131.25    22.270.426dbp ( mmhg)67.22    5.8571.21    4.8757.50.05974.36    8.0975.34 8.9883    16.260.303table  2clinical and biochemical data subjects when classified in accordance to the genotype of the g / a polymorphisms at positions 238 of the tnf- gene promoterunder 18above 18traitgg ( 33)ga ( 8)aa ( 0)pgg ( 175)ga ( 38)aa ( 3)page ( years)13.24    2.9612.62    2.210.58542.18    15.0139.93    16.5042.50    21.070.585sex ( m / f)13/204/40.58997/6017/210.745bmi ( kg / m)20.12    3.5819.08    2.880.45426.40    4.3726.84    4.7123.37    3.120.415fbs ( mg / dl)87.63    6.2484.50    6.830.21889    41.6287.25    23.1389    13.470.766homa10.79    6.4210.28 3.030.82812.13    8.8510.15    9.1810.19    1.040.158cho ( mg / dl)162.18    23.99146.38    26.830.110199.08    40.46183.78    37.69214.17    92.590.090hdl - c ( mg / dl)43.83    7.6243.12    7.800.81642.85    9.0342.18    10.2541.66    4.190.904ldl - c ( mg / dl)100.08    19.5287.30    27.620.134125.92    34.11112.62    32.22148.07    83.890.052tg ( mg / dl)94.30    37.8580    30.230.328123.00    97.55145.25    57.70103.50    56.730.519whr0.82    0.040.8    0.110.4510.87    0.080.87    0.10.83    0.110.780sbp ( mmhg)100.42    8.51104.56    7.720.217115.14    15.20115.86    15.04103    21.650.757dbp ( mmhg)66.33 6.650.407table  3clinical and biochemical data of subjects when classified in accordance to bmi for polymorphisms at positions 308 of the tnf- gene promoterunder 18above 18traitgrade 1grade 2pgrade 1grade 2grade 3pbmi  <  85%bmi  >  85%bmi  <  2525    bmi  <  30bmi    30(n  =  26)(n  =  16)(n  =  75)(n  =  81)(n  =  46)gg21(80.8%)13(81.2%)67(89.3%)71(87.7%)37(80.4%)ga5(19.2%)2(12.51%)8(10.7%)10(12.3%)7(15.2%)aa1(6.2%)2(4.3%)age ( years)12.88    2.7612.53    2.810.69236.37    16.6545.56    14.3649.85    11.460.000bmi ( kg / m)17.64    2.032.60    23.630.00022.27    1.9327.49    1.4232.90    3.370.000fbs ( mg / dl)86.34    6.2186.34    6.210.94887    21.0791    16.6691.50    26.020.001homa9.94 4.8010.22    6.270.87012.34    10.1812.47    413.4010.31    5.780.071cho ( mg / dl)155.9    22.13169.03    25.490.086181.50    42.11201.32    43.50213.51    36.660.000hdl - c ( mg / dl)43.19    7.7444.59    9.930.61242.53    9.1836.98    8.3745.62    11.340.005ldl - c ( mg / dl)96.12    19.71102.79    23.820.332113.77    36.47125.82    34.53136.71    32.790.002tg ( mg / dl)86.78    27.92108.37    49.330.077108    67.10154.50    117.21135.25    70.220.000whr0.81    0.050.86    0.060.0080.83    0.070.89    0.080.9    0.070.000sbp ( mmhg)100.78    8.14103.15    7.650.355111.50    11.78116    18119    17.750.000dbp ( mmhg)67.51    6.3667.87    5.520.85471.57    7.2375.51    8.1177.79    8.690.000table  4clinical and biochemical data of subjects when classified in accordance to bmi for polymorphisms at positions 238 of the tnf- gene promoterunder 18above 18traitgrade 1grade 2pgrade 1grade 2grade 3pbmi  <  85%bmi  >  85%bmi  <  2525    bmi  <  30bmi    30(n  =  26)(n  =  16)(n  =  75((n  =  81)(n  =  46)gg21(80.8%)13(80%)65(81.2%)60(77.9%)32(78%)ga5(19.2%)2(20%)13(16.2%)16(20.8%)9(22%)aa2(2.5%)1(1.3%)age ( years)13.50   2.75   12.46   2.90  0.264 38   16.61  42.42   13.85    50.24   12.16  0.000bmi ( kg / m)18.05   2.28   23.15   2.63   0.00022.27   1.89   27.50   1.43   32.57   3.18   0.000fbs ( mg / dl)86.86    7.21 87.30   4.88   0.83787   54   89   26.03   92   15.04   0.011homa10.97   5.69   10.21   6.39   0.69611.32   8.92   12.14   9.73   10.44    6.73 0.385cho ( mg / dl)154.36   22.76   167.30   27.41   0.112186.30   41.59   200.50   42.15   208.26   34.04   0.011hdl - c ( mg / dl)42.19   6.31   46.30   8.99   0.09443.35   8.64   40.66   8.26   45.30   11.39 0.023ldl - c ( mg / dl)95.35   19.41   101.44   25.09   0.391117.18   36.66   126.27   34.73   131.60   30.38   0.071tg ( mg / dl)87.8   29.78   97.93   46.60   0.4110.50    69.11 144.50   111.46   135   69.81   0.000whr0.80   0.06   0.85   0.05   0.012 0.83   0.08  0.89   0.08   0.89   0.08   0.000sbp ( mmhg)99.4   8.42   104.4   7.71   0.067111.75   12.67   115   14.84   118.5    17.34 0.001dbp ( mmhg)66.94   5.68   67.30   5.45   0.84572.11 7.22   74.13   7.54   78.09    7.87 0.000 clinical and biochemical data of subjects when classified in accordance to the genotype of the g / a polymorphisms at positions 308 of the tnf- gene promoter clinical and biochemical data subjects when classified in accordance to the genotype of the g / a polymorphisms at positions 238 of the tnf- gene promoter clinical and biochemical data of subjects when classified in accordance to bmi for polymorphisms at positions 308 of the tnf- gene promoter clinical and biochemical data of subjects when classified in accordance to bmi for polymorphisms at positions 238 of the tnf- gene promoter the purpose of the present study is to determine whether the g    a polymorphisms of the tnf- gene promoter are associated with obesity and anthropometric parameters in cohort tehran lipid and glucose study . there are no associations between g-308a and g-238a tnf- promoter polymorphisms and increases in bmi . tnf- is one of the cytokines secreted from adipose tissue in obesity ; it can be a candidate gene to inspect obesity and related diseases . obesity is a complex metabolic disorder with a strong genetic component and there are many candidate genes for obesity and its related phenotypes . most of these genes are candidate because their mutations cause rare genetic syndromes affecting adipocytes differentiation . recent interest has focused on the role of the tnf- gene in insulin resistance and obesity . we therefore examined the association between the polymorphism of tnf- and obesity without metabolic disease . it came as another study reported an association between this genetic marker and excessive fat accumulation in women . moreover , a potential role for the tnf- locus in obesity is also supported by a linkage study , which reported a relationship between the tnf- locus and various global measures of adiposity in pima indians and european caucasians [ 11 , 12 ] however , it is located within a consensus sequence for the transcription factor ap-2 in the promoter region of the gene . the g-308a mutation in the promoter region of tnf- acts in vitro as a much stronger transcriptional activator than the wild - type tnf- and it is suggested that a higher transcriptional activity would result in higher tnf- concentrations followed by decreased insulin sensitivity . so this variant could play a role in the development of obesity and related phenotypes . interestingly , obesity is known to be associated with increased levels of tnf- mrna and protein in fat tissue both in humans and in genetically obese or diabetic rodents . moreover , a study has shown that the tnf- mrna level in adipose tissue are significantly correlated with the percentage of body fat in human obese subjects . a recent study , while confirming linkage between the tnf- locus and obesity in families of french - canadian origin , has also found a significant association between this locus and high blood pressure . a significant positive correlation between serum tnf- concentration and systolic blood pressure has also been reported among individuals of an isolated native canadian population over a wide range of adiposity . an italian population study suggests that the g-308a mutation of the tnf- gene is unlikely to play an important role in the development of obesity and its related metabolic abnormalities such as insulin resistance and dyslipidemia . as for the g-238a variant , a study of non - diabetic relatives and control subjects in britain showed that the 238 variant was associated with increased insulin sensitivity as estimated by two independent methods . a recent meta - analysis ( 2,106 cases and 2,920 controls ) of the rs361525 ( g-238a ) variant has not detected a significant association with type 2 diabetes , nor has the study of caucasian and african american subjects . benedicte fontaine - bisson and co - workers suggest that the 238 g    a and 308 g    a polymorphisms of tnf- alter circulating free fatty acids and insulin resistance in obese subjects with type 2 diabetes mellitus .