Objective: Certain human leukocyte antigen (HLA)-DR,DQ genotypes have been associated with type 1 diabetes mellitus (T1DM) risk, although it is unknown whether the association is due to alleles, haplotypes, genotypes, the formation of heterodimers, or all of the above. To characterize the role of the HLA-DR,DQ genotype and ethnicity on the onset age of T1DM, we analyzed these factors in patients with T1DM and the general population.
Methods: One thousand three hundred twenty-two well-characterized patients with T1DM were compared with 3339 children from the general population of Denver, Colorado, USA. Because of the extensive available data across age and ethnic groups, this study population is unique.
Results: The HLA-DR3/4,DQB1*0302, DRX/4,DQB1*0302 (where X=1, 4, 8, and 9), and HLA--DR3/3 genotypes were associated with T1DM, supporting previous research. Additionally, the DR3/9 genotype showed a positive association with T1DM, which has not previously been described in Caucasian populations. The HLA-DR3/4*0302 genotype was most strongly associated with T1DM in diabetic individuals with the youngest onset age. Genotype frequencies were similar between Hispanics and non-Hispanic whites, except for the DR3/3 genotype, which was more likely to be found in non-Hispanic whites.
Conclusions: These results indicate that there are multiple alleles and genotypes associated with T1DM and that the risk associated with different genetic markers depends on the age of disease onset, suggesting that some markers may be involved in more rapid disease progression.