To study the human leukocyte antigen (HLA)-DQB1 genetic background in the Chinese population in Taiwan and its association with the low incidence of insulin-dependent diabetes mellitus (IDDM) in this population.
Forty-eight IDDM patients and 59 nondiabetic unrelated control subjects were recruited from the population in Taiwan. HLA-DQB1 exon 2 was enzymatically amplified by polymerase chain reaction. HLA-DQBl alleles were diagnosed by dot blotting and hybridization with 16 sequence-specific oligonucleotide probes.
DQB1*0201 and DQB1*0302 alleles were more frequent and DQB1*0301 and DQB1*0601 were less frequent in Chinese with IDDM than in control subjects. Genotypes for homozygous non-aspartic acid residue (NA/NA) at position 57 were positively associated with IDDM at a relative risk of 4.34 (P < 0.001), and those for homozygous aspartic acid (A/A) were negatively associatedwith IDDM at a relative risk of 0.14 (P < 0.001). Among the NA/A heterozygotes, only DQB1*0201/ DQB1*0303 was significantly increased in IDDM subjects.
The amino acid residue at position 57 of HLA-DQ β3-chain is significantly associated with the development or prevention of IDDM in Chinese subjects living in Taiwan. Other genetic and environmental factors may also play important roles in pathogenesis of IDDM.