Associations of MHC class II alleles with insulin-dependent diabetes mellitus (IDDM) in patients from North India

Thirty-four insulin-dependent diabetes mellitus (IDDM) patients from North India were studied with respect to their HLA class II alleles including tho se of the DRB1, DQA1, DQB1 and DPB1 loci, using the polymerase chain reacti on (PCR) and hybridization with sequence-specific oligonucleotide probes (S SOP). They were compared with the class II alleles of 94 normal adult contr ols from the same ethnic background. The results show a statistically signi ficant increase of DRB1*03011 (p < 0.00001), DQB1*0201 (p < 0.007), DQA1*05 01 (0.0037) and DPB1*2601 (p < 0.0042) in patients compared to controls. DR *04 was not significantly increased. However, homozygosity for DRB1*03011 w as increased more than expected. DRB1*1501 and *1502 did not show a signifi cant decrease in the patients. However, DRB1*0701 was decreased significant ly, but this difference did not remain significant when the p, value was co rrected fur the number of alleles tested. Similarly, DPB1*2601 was increase d significantly in the patients but did not remain significant after p was corrected for the number of alleles tested. However, DPB1*2601 was in creas ed, and remained significant after correction, in patients not having HLA-D R3. We also studied the possible role of aspartic acid at codon 57 of the D Q beta chain in protection against development of diabetes, and arginine at codon 52 of the DQ alpha chain in susceptibility. We observed an increase in non-Asp(57) alleles in DQ beta and Arg(52) in DQ alpha in the patients, however, this effect seems to be due to che fact that the most prevalent ha plotype in diabetic patients. DRB1*03011-DQA1*0501-DQB1*'0201, has DQB1 and DQA1 alleles which carry non-Asp(57) and Arg(52), respectively. (C) Americ an Society for Histocompatibility and Immunogenetics, 1999. Published by El sevier Science Inc.