High frequency of HLA-DQB1 non-Asp(57) alleles in Kuwaiti children with insulin-dependent diabetes mellitus.

The prevalence of polymorphic amino acids at position 57 of the HLA DQB1 in Kuwaiti children with insulin-dependent diabetes mellitus (IDDM) and nondiabetic controls has been determined using a polymerase chain reaction-sequence-specific primers (PCR-SSP) method. Using this approach, 34/55 (62%) IDDM children were found to be homozygous Ala/Ala and 19/55 (35%) were heterozygous with various combinations. Amongst the IDDM children with heterozygous genotype at codon 57 of HLA DQB1, 6/55 (11%) had Asp/Ala, 8/55 (15%) had Ala/Val, 4/55 (7%) had Ala/Ser and 1/55 had Asp/Val allelic combinations. When considered collectively, the nonaspartate (NA) alleles were represented in 87% of the IDDM cases and only 13% cases had Asp(57) allele in different heterozygous combinations, while none of the IDDM subjects had a homozygous Asp genotype. In nondiabetic controls, homozygous non-Asp (NA) alleles were represented in 44% subjects, 37% of the controls were heterozygous (NA/A) and 19% had a homozygous (A/A) genotype. These differences between the IDDM group and the control group were found to be statistically significant. Our data report one of the highest frequency of NA/NA residues at this locus compared with that from different world populations (Sardinians, Norwegians, US Caucasians, US Blacks and Chinese).