Strategies for evaluating idiopathic inflammatory myopathy disease susceptibility genes.

This review outlines the progress that has been made in understanding the genetics of the idiopathic inflammatory myopathies in the previous 2 years, with a particular focus on dermatomyositis and polymyositis. A recent genome-wide association study in dermatomyositis has confirmed the importance of the major histocompatibility region in this disease, and has suggested a shared genetic etiology with other autoimmune disorders. This has led to an ongoing study of additional immune-related loci using the Immunochip array. Candidate gene studies have identified novel risk associations in non-Europeans, such as STAT4 and HLA-DRB1 in the Japanese population. Evidence for gene-environment interactions has come from two recent studies implicating smoking status and statin use with HLA alleles. This review also touches on future approaches to genetic research in myositis, including bioinformatics tools to identify causal variants, HLA imputation from existing genetic data and statistical methods to investigate shared effects between subgroups of myositis.