ASSOCIATION OF HLA-DPB1(ASTERISK)0301 WITH IDDM IN MEXICAN-AMERICANS

Susceptibility to IDDM has been associated with specific alleles at th e HLA class II loci in a variety of human populations. Previous studie s among Mexican-Americans, a group ancestrally derived from Native Ame ricans and Hispanic whites, showed that the DR4 haplotypes (DRB10405- DQB10302 and DBB1*0402-DQB1*0302) and the DR3 haplotype (DRB1*0301-DQ B10201) were increased among patients and suggested a role for both D R and DQ alleles in susceptibility and resistance. Based on the analys is of 42 Mexican-American IDDM families and ethnically matched control subjects by polymerase chain reaction/sequence-specific oligonucleoti de probe typing, we report an association of IDDM with the DPB1 allele , 0301 (relative risk = 6.6; P = 0.0012) in this population. The anal ysis of linkage disequilibrium patterns in this population indicates t hat the observed increased frequency in DPB10301 among patients canno t be attributed simply to linkage disequilibrium with highrisk DR-DQ h aplotypes. These data suggest that in addition to alleles at the DRB1 and DQB1 loci, polymorphism at the DPB1 locus may also influence IDDM risk.