HLA-DRB1 and juvenile dermatomyositis: These Immunochip studies of 2566 cases with IIM of European ancestry identified a strong signal in the MHC region meeting genome-wide significance (p< 5x10-8), with association to alleles of the 8.1 ancestral haplotype; HLA-DRB1*03:01 in PM and juvenile-onset dermatomyositis (JDM), and HLA-B*08:01 in adult-onset DM (6).