Ethnic Differences in Human Leukocyte Antigen Markers of Susceptibility to IDDM

OBJECTIVE To determine whether genetic differences explain the lower risk of developing insulin-dependent diabetes mellitus (IDDM) for Hispanic versus non- Hispanic white children in Colorado. RESEARCH DESIGN AND METHODS Hispanic (n = 62) and non-Hispanic white (n = 82) subjects with IDDM identified from the Colorado IDDM Registry and healthy, nondiabetic control subjects were recruited. Human leukocyte antigen (HLA) serologic typing and sequence-specific oligonucleotide typing of DQA1 and DQB1 alleles were performed. RESULTS HLA and allele associations with IDDM were similar in both ethnic groups. HLA-DR3 and HLA-DR4 were more common in IDDM subjects in both ethnic groups. Subjects with DQB1 alleles encoding aspartic acid (Asp) in position 57 were less likely to have IDDM, irrespective of ethnic background. HL A-DR3 was less common among Hispanic subjects than non-Hispanic white control subjects (4.4 vs. 17.5%, Hispanics vs. non-Hispanic whites, P = 0.04). CONCLUSIONS These data suggest that the lower prevalence of HLA-DR3 in the Hispanic population, a pattern consistent with the presence of Amerindian admixture, may explain the lower rate of IDDM in the Hispanic population.