For example, type 1 diabetes mellitus (T1DM) is an autoimmune disorder with a substantial genetic component, where HLA class II gene variants such as DQA1*0301, DQB1*0302, DQA1*0501, DQB1*0201, DQB1*060, DQB1*0302 (DR4), DRB1*03 and DRB1*04 account for 30-50% of its heritability (10, 19, 20). The gene discussed is HLA-DRB1; the disease is type 1 diabetes mellitus.