All participants carried at least 1 copy of one of the T1D high-risk HLA class II alleles, DRB1*04, DRB1*03, or DQB1*03; 15 participants carried DR4 only, 3 were DR3/DR4, and 5 were DR3 only. The gene discussed is HLA-DRB1; the disease is type 1 diabetes mellitus.