Japanese Patients With Type 1 Diabetes

not only regulates calcium metabolism but also modulates the immune system. Some reports have suggested that 1,25(OH)2D3 helps to prevent the devel-opment of type 1 diabetes. The associa-tion between the vitamin D receptor (VDR) genotype and susceptibility to type 1 diabetes has been examined, but a de-finitive conclusion has not yet been reached (1,2). We examined the VDR ge-notype in juvenile Japanese patients with type 1 diabetes. A total of 108 diabetic patients (41 boys and 67 girls, age of onset 0.4–18 years with a median age of 8.9) and 120 nonrelated nondiabetic subjects were studied. Three polymorphic restriction f ragment – length polymorphisms (RFLPs), i.e., Fok I, ApaI, and TaqI, were genotyped by PCR-RFLP method. The ge-notype or allele frequencies were com-pared statistically by the 2 test. The significance of differences in each geno-type for the age of onset was tested with the Mann-Whitney U test. Among the patients, the FF (n 50) and tt (n 5) genotypes were found rel-atively frequently, and aa (n 46) was infrequent compared with those in con-trol subjects, but these differences were not statistically significant (P 0.14, 0.18, and 0.38 for FF, tt, and aa geno-types, respectively). There was also no significant difference in the allele fre-quency of each polymorphism, although the incidence of the F allele tended to be higher in the diabetic patients (P 0.051). Concerning the age of onset of diabetes, patients with the ff genotype (n 12, median 5.2 years, range 1.7– 11.0) were significantly younger at onset than those with FF (n 50, 9.7 years