Serum amyloid A1 (SAA1) gene polymorphisms in Japanese patients with adult-onset Still's disease
Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder in which inflammasome activation plays a pathophysiological role. In view of the inflammatory nature of AOSD, we investigated whether serum amyloid A (SAA) gene polymorphisms affect the susceptibility of patients with AOSD.Eighty-seven Japanese patients with AOSD and 200 healthy Japanese subjects were recruited in this study. The genotypes of the -13C/T SNP in the 5'-flanking region of the SAA1 gene (rs12218) and two SNPs within exon 3 of SAA1 (2995C/T and 3010C/T polymorphisms) were determined using polymerase chain reaction fragment length polymorphism (PCR-RFLP) assay in all subjects. In AOSD patients, exons 1, 2, 3, and 10 of the MEFV gene were also genotyped by direct sequencing.The frequency of the SAA1.3 allele was increased in AOSD patients compared with that in healthy subjects (43.1% versus 37.5%), but the difference was not significant. The -13T allele was more frequently observed in AOSD patients than in healthy subjects (50.6% versus 41.0%, P = .0336). AOSD patients with the -13T allele had been treated with immunosuppressants more frequently than those without this allele. MEFV mutations were detected in 49 patients with AOSD (49/87, 57.3%). AOSD patients with MEFV variants frequently exhibit macrophage activation syndrome, but the difference was not significant (34.7% versus 18.4%, P = .081). Also, there was no significant difference in SAA1 -13C/T allele frequency between AOSD patients with and without MEFV mutations.Our data shows a significant association between T allele of rs12218 and AOSD in Japanese population.