Association of the leukocyte immunoglobulin G (Fcγ) receptor IIIa-158V/F polymorphism with inflammatory myopathies in Dutch patients

Leukocytes are involved in the pathogenesis of idiopathic inflammatory myopathies (IIMs). Immunoglobulin G (IgG) receptors (FcγR) link the specificity of IgG to the effector functions of leukocytes. Several FcγR subclasses display functional polymorphisms that determine in part the vigour of the inflammatory response. FcγRIIIa genotypes were differentially distributed among 100 IIM patients compared with 514 healthy controls with a significant increase of the homozygous FcγRIIIa-V-158 genotype (3 × 2 contingency table, χ² = 6.3, P  = 0.04). Odds ratios (ORs) increased at the addition of each FcγRIIIa-V-158 allele, in particular among patients with non-specific myositis and dermatomyositis {OR 2.1 95% confidence interval (CI) 1.1–4.3] and 2.7 (95% CI 1.1–6.4) for FcγRIIIa-V/F158 and FcγRIIIa-V/V158 genotypes, respectively, using FcγRIIIa-F/F158 as a reference group}. These data suggest that the FcγRIIIa-V-158 allele may constitute a genetic risk marker for IIM.