This review focuses on the advances that have been made in understanding the genetics of the idiopathic inflammatory myopathies (IIM) in the past 2 years, with a particular emphasis on polymyositis, dermatomyositis and inclusion body myositis. Two large human leukocyte antigen (HLA) imputation studies have confirmed a strong association with the 8.1 ancestral haplotype in clinical subgroups of myositis and suggest multiple independent associations on this haplotype. A large genetic study in 2566 IIM patients revealed associations such as PTPN22, STAT4, UBE2L3 and BLK, which overlap with risk variants reported in other seropositive autoimmune diseases. There is also evidence of different genetic architectures in clinical subgroups of IIM. Future approaches, such as sequencing and trans-ethnic meta-analyses, will further advance the understanding of IIM genetics.
