LOW-PREVALENCE OF IMMUNOGENETIC MARKERS OF IDDM IN ADULT KOREANS WITHDIABETES DETECTED ON OGTT

In the Asian populations, it is not uncommon for adult patients with N IDDM to eventually lose beta-cell function and develop IDDM. Accepting that IDDM is an autoimmune disease, which occurs on a genetic backgro und, it could be hypothesized that by measuring autoantibody prevalenc e and HLA DQ gene polymorphism, known important prediagnostic markers of IDDM, the prevalence of adult-onset IDDM in patients with previousl y undiagnosed NIDDM patients could be estimated. To do this, anti-GAD prevalence and HLA-DQ Al and DQ B1 polymorphisms after PCR amplificati on of genomic DNA were analyzed in 121 newly diagnosed diabetic patien ts of Yonchon cohort and compared to the results with those of 100 mat ched healthy control subjects. We also compared the results with those of other populations to assess the difference of genotype distributio n. The overall prevalence of anti-GAD antibodies was 1.7% (2 of 121) i n patients with previously undiagnosed NIDDM, whereas 1 of 100 control s had positive antibodies. Among those who were positive, their titer of antibodies to GAD were not high. No statistically significant diffe rences in the distribution of either mean levels of anti-GAD or DQA1 a nd DQB1 alleles were found comparing NIDDM patients to controls. Inter estingly, the frequency of DQB1non-Asp-57 and DQA1*Arg-52 alleles in the Korean adult control population was similar to that of US Caucasia ns (DQB1non-Asp-57: 0.431 vs. 0.475; DQA1*Arg-52: 0.492 vs. 0.463). T he low prevalence of anti-GAD antibodies and HLA-DQA1 and DQB1 suscept ibility alleles among recent-onset NIDDM patients, not different compa red to controls suggests that diabetes in Korean adults is unlikely to have an autoimmune component to its pathogenesis.