LACK OF ASSOCIATION OF THE INSULIN GENE REGION WITH TYPE-1 (INSULIN-DEPENDENT) DIABETES-MELLITUS IN JAPANESE SUBJECTS

Although the insulin gene region is implicated in susceptibility to Type 1 (insulin-dependent) diabetes mellitus in Caucasians, significance of this region to Type 1 diabetes in Japanese remains unclear because the class 1 alleles (shorter insertion) of the variable number of tandem repeat in the 5' region of the insulin gene are predominant in both diabetic and nondiabetic subjects. The 5' insulin gene polymorphism was analysed in 75 Japanese patients and 69 control subjects with a precise method using PvuII and a polymorphism specific probe, which enabled us to divide class 1 alleles into four subclasses. Allelic frequencies were not significantly different between Type 1 diabetic patients and control subjects. The polymorphism in the 3' untranslated region of the insulin gene (1127/PstI) was also analysed and found to be tightly linked to the 5' insulin gene polymorphism, and thus was not associated with diabetes. Interaction between HLA-DR and the insulin gene region, which was reported in the French study, was not observed in Japanese. These results suggest that the insulin gene region is not a valuable genetic risk factor for Type 1 diabetes in Japanese.