ABSTRACT
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 DQBl alleles encoding aspartic acid (Asp) in position 57 were less likely to have IDDM, irrespective of ethnic background. HLA-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.
Subject(s)
Diabetes Mellitus, Type 1/genetics , Diabetes Mellitus, Type 1/immunology , Ethnicity , HLA-A Antigens/blood , HLA-B Antigens/blood , HLA-D Antigens/blood , Adolescent , Adult , Alleles , Case-Control Studies , Child , Child, Preschool , Colorado , Diabetes Mellitus, Type 1/epidemiology , Disease Susceptibility , Female , HLA-A Antigens/genetics , HLA-B Antigens/genetics , HLA-D Antigens/genetics , HLA-DQ Antigens/blood , HLA-DQ Antigens/genetics , HLA-DQ alpha-Chains , HLA-DQ beta-Chains , HLA-DR Antigens/blood , HLA-DR Antigens/genetics , Hispanic or Latino , Humans , Male , Odds Ratio , Registries , White PeopleABSTRACT
OBJECTIVE: To compare the clinical characteristics of IDDM in HD and NHWD subjects in order to evaluate potential heterogeneity of IDDM by ethnicity. RESEARCH DESIGN AND METHODS: HD subjects (n = 73) and NHWD subjects (n = 97) were recruited from the Colorado IDDM Registry. The registry included individuals who were Colorado residents, less than 18 yr old at diagnosis, placed on insulin within 2 wk of diagnosis, and had diabetes not secondary to other conditions. Residual beta-cell function was measured as the 1-h C-peptide response to a Sustacal challenge. RESULTS: HD subjects were similar to NHWD subjects in insulin dose, HbA1, HLA-DR antigens, ICAs, and family history of IDDM. HD subjects were more likely to have a family history of NIDDM than NHWD subjects (11 vs. 3%, P = 0.03). HD girls had higher C-peptide levels (0.27 vs. 0.11 nm/L [0.83 vs. 0.33 ng/ml], P = 0.01), BMI (22.7 vs. 20.9 kg/m2 P = 0.04), subscapular skinfold thickness (18.9 vs. 15.0 mm, P = 0.04), and WHR (0.81 vs. 0.77, P = 0.03) than NHWD females. After controlling for diabetes duration, BMI, sex, and family history of NIDDM, residual beta-cell function was associated significantly with Hispanic ethnicity, although the term accounted for just 3% of the overall variability in C-peptide levels. CONCLUSIONS: Little evidence of heterogeneity by ethnicity of IDDM patients in the Colorado IDDM Registry was found. Ethnic differences in C-peptide levels may be related to differences in body fat distribution in females rather than heterogeneity of the disease.
