Immunogenetic features in 120 Japanese patients with idiopathic inflammatory myopathy.

OBJECTIVE: To examine the role of HLA-DRB1 and tumor necrosis factor (TNF) promoter genotypes in the development and the autoantibody profiles of idiopathic inflammatory myopathy (IIM) in Japanese patients. METHODS: HLA-DRB1 and TNF promoter genotypes were determined, and serum antinuclear autoantibodies were identified in 120 adult Japanese patients with IIM [72 with dermatomyositis (DM), 30 with polymyositis (PM), 18 with myositis overlapping with other collagen vascular diseases], as well as in 265 controls. RESULTS: Forty-two patients (35%) were positive for myositis-specific autoantibodies (MSA), including 37 (31%) for anti-aminoacyl-tRNA synthetase (ARS) autoantibodies. Allele carrier frequency of HLA-DRB1*0803 was increased in the patients with IIM [p = 0.02, corrected p (pc) NS, 23% vs 14%, odds ratio (OR) = 1.9 (95% confidence interval, CI = 1.1-3.2)], with PM [p = 0.006, pc NS, 33%, OR 3.1 (95% CI 1.3-7.1)], and with anti-ARS autoantibodies [27%, p = 0.04, OR 2.3 (95% CI 1.0-5.1)] compared with controls. DRB1*0405 was increased in patients with anti-ARS autoantibodies compared with controls [41% vs 25%, p = 0.04, pc NS, OR 2.1 (95% CI 1.0-4.3)]. TNF promoter genotype was associated with the presence of interstitial lung disease (ILD). The carriage of a TNF-a haplotype formed by -1031C, -863A, and -857C was increased in the patients with ILD versus those without ILD [33% vs 18%, p = 0.05, pc NS, OR 2.3 (95% CI 0.94-5.5)]. CONCLUSION: HLA-DRB1 alleles were associated with development of IIM and MSA in a Japanese population.