The distribution of HLA-DRB1*03 was uneven among subgroups of IIM, which varied from 75.4% in patients with IBM with an OR of 8.71 (5.48–13.8) to 59.5% in patients with PM with an OR of 4.16 (3.15–5.48), 47.6% in patients with DM with an OR of 2.57 (1.90–3.49) and 45.5% in patients with JDM with an OR of 2.36 (1.56–3.79). This evidence concerns the gene HLA-DRB1 and dermatomyositis.