Type I diabetes environmental factors and correspondence analysis of HLA class II genes in the Yemenite Jewish community in Israel

OBJECTIVE - The Israeli Yemenite Jewish community has displayed an exceptio nally rapid increase in the frequency of type 1 diabetes, having the highes t rate of all Israeli ethnic groups We studied the role of the environment. in relation to the nature and frequency of HLA class Ii gents. to evaluate its possible involvement in the development of diabetes RESEARCH DESIGN AND METHODS - We interviewed 196 elderly Yemenite women, wh o had immigrated to Israel as adults, in programmed encounters about signs and symptoms of type 1 diabetes. infant feeding customs, and infectious dis eases in Yemen. We also performed HLA oligotyping of DRB1, DQA1, and DQB1 g enes in 120 unrelated Yemenite Jews, including 44 type diabetic patients an d 76 healthy control subjects, and used these data in correspondence analys is comparing Yemenites with different Israeli ethnic groups. RESULTS - Interviews indicated that early exposure to cow's milk was very c ommon in Yemen However, none of the women could recall classical presentati ons of diabetes HLA oligotyping showed that gene frequencies of non-Asp-57 (of the HLA-DQB chain) in the patients (0.94) and control subjects (0.6) we re similar to those of other populations with a known high incidence of typ e 1 diabetes. Correspondence analysis revealed that Yemenite Jews are genet ically distinct from other ethnic groups in Israel. CONCLUSIONS - The genetic distinctiveness of Yemenite Jews may explain thei r unusually high incidence of type 1 diabetes in Israel. Despite the presen ce of highly susceptible diabetogenic HLA class II genes in this community. early exposure to cow's milk did not cause phenotypic expression of diabet es in Yemen. This finding suggests that in this population. either cow's mi lk dues not play a crucial role in triggering diabetes, or environmentally conferred protection, such as frequent infectious disease in Yemen. was dom inant.