HLA-DR specificities among black Americans with juvenile-onset diabetes.

To study the association of histocompatibility (HLA) genes in black persons with juvenile-onset diabetes, we determined HLA-A, HLA-B, HLA-C and HLA-DR specificities in 40 black Americans with this disease and in 67 unaffected black Americans. Marked increases in the frequencies of HLA-DRw3 and HLA-DRw4 were found in the patients as compared with the unaffected persons: DRw3 was found in 72.5 per cent of patients versus 29.9 per cent of unaffected persons and DRw4 in 72.5 per cent versus 25.4 per cent (corrected P values each less than 0.0007). DRw2 was not found in any of the patients but was present in 26.9 per cent of unaffected persons (P corrected less than 0.035). There is thus a negative correlation between this specificity and juvenile-onset diabetes. By contrast, no meaningful differences were found in the frequencies of A, B, or C locus antigens. Studies in white persons with juvenile-onset diabetes have suggested that the reported HLA-B associations are due to HLA-D region specificities, and our results also support the premise that D region specificities are the primary associations with juvenile-onset diabetes.