Objectives: To investigate associations between signal transducer and activator of transcription 4 (STAT4), one of the most commonly acknowledged genes for the risk of multiple autoimmune diseases, with susceptibility to adult-onset polymyositis/dermatomyositis among Japanese individuals.
Methods: A single nucleotide polymorphism of STAT4, rs7574865, was genotyped using TaqMan assay in 1143 Japanese individuals. The first set comprised 138 polymyositis/dermatomyositis patients and 289 controls and the second set comprised 322 patients and 394 controls. 460 patients (273 polymyositis and 187 dermatomyositis patients) and 683 controls were genotyped.
Results: rs7574865T conferred a risk of polymyositis/dermatomyositis with an OR of 1.37 (95% CI 1.16 to 1.64; p=4x10(-4); p(corr)=0.0012). Both polymyositis and dermatomyositis exhibited high associations with the rs7574865T allele (polymyositis: OR=1.36, 95% CI 1.11 to 1.67; p=0.0039; p(corr)=0.012; dermatomyositis: OR=1.40, 95% CI 1.10 to 1.78; p=0.0054; p(corr)=0.016). The association between this STAT4 polymorphism and interstitial lung disease (ILD) was also investigated in the first set of polymyositis/dermatomyositis patients (n=138); those with ILD (n=79) bore rs7574865T more frequently compared with controls (OR 1.59, 95% CI 1.10 to 2.28; p=0.013; p(corr)=0.039).
Conclusion: This is the first study to show a positive association between a STAT4 polymorphism and polymyositis/dermatomyositis, suggesting that polymyositis/dermatomyositis shares a gene commonly associated with the risk of other autoimmune diseases.