OBJECTIVE: To identify new genetic associations with juvenile and adult dermatomyositis (DM). METHODS: We performed a genome-wide association study (GWAS) of adult and juvenile DM patients of European ancestry (n = 1,178) and controls (n = 4,724). To assess genetic overlap with other autoimmune disorders, we examined whether 141 single-nucleotide polymorphisms (SNPs) outside the major histocompatibility complex (MHC) locus, and previously associated with autoimmune diseases, predispose to DM. RESULTS: Compared to controls, patients with DM had a strong signal in the MHC region consisting of GWAS-level significance (P < 5 × 10(-8)) at 80 genotyped SNPs. An analysis of 141 non-MHC SNPs previously associated with autoimmune diseases showed that 3 SNPs linked with 3 genes were associated with DM, with a false discovery rate (FDR) of