HLA-A, B, C and DR antigens in young South African blacks with Type 1 (insulin-dependent) diabetes mellitus.

The HLA status of South African black Type 1 (insulin-dependent) diabetic patients with age of onset under 35 years was compared with that of healthy black control subjects. HLA-A, B and C antigens were determined in 94 patients and 995 control subjects, while DR typing was carried out on 56 patients and 195 control subjects. There was a significant increase in the frequency of DR4 in patients as compared with control subjects (p less than 0.01; relative risk 3.4). DR3/DR4 heterozygosity was associated with a greater relative risk for developing Type 1 diabetes mellitus (3.7) than the presence of DR3 alone (relative risk 1.6). A significant negative association was observed between the presence of BW42 and Type 1 diabetes in this population sample (p less than 0.04; relative risk 0.3). A similar trend was observed with regard to DR2, the corrected p value just attaining statistical significance (p less than 0.05; relative risk 0.1).