Islet cell antibody-positive relatives with human leukocyte antigen DQA1*0102, DQB1*0602: Identification by the diabetes prevention trial-type 1

The presence of human leukocyte antigen (HLA) haplotype DQA1*0102, DQB1*060 2 is associated with protection from type 1 diabetes. The Diabetes Preventi on Trial-type 1 has identified 100 islet cell antibody (ICA)-positive relat ives with this protective haplotype, far exceeding the number of such subje cts reported in other studies worldwide. Comparisons between ICA(+) relativ es with and without DQB1*0602 demonstrated no differences in gender or age; however, among racial groups, African-American ICA relatives were more lik ely to carry this haplotype than others. The ICA(+) DQB1*0602 individuals w ere less likely to have additional risk factors for diabetes [insulin autoa ntibody (IAA) positive or low first phase insulin release (FPIR)] than ICA( +) relatives without DQB1*0602. However, 29% of the ICA(+) DQB1*0602 relati ves did have IAA or low FPIR, Although half of the ICA(+) DQB1*0602 relativ es had a high risk second haplotype, this was not associated with the addit ional risk factors for diabetes. Hispanic ICA(+) individuals with DQB1*0602 were more likely to be IAA positive or to have low FPIR than other racial groups. In conclusion, the presence of ICA in the relatives described here suggests that whatever the mechanism that protects DQB1*0602 individuals fr om diabetes, it is likely to occur after the diabetes disease process has b egun. In addition, there may be different effects of DQB1*0602 between ethn ic groups.