Dense genotyping of immune-related loci in idiopathic inflammatory myopathies confirms HLA alleles as the strongest genetic risk factor and suggests different genetic background for major clinical subgroups.
PTPN22 SNPs were assessed in a large, cross-sectional, case-control study from the UK involving patients with adult or juvenile IIM, comprising patients with polymyositis (PM) (n=114), dermatomyositis (DM) (n=102), myositis associated with another connective tissue disease (myositis-CTD overlap syndrome) (n=64), or juvenile DM (n=101), in comparison with 748 control subjects.