LOCALIZATION OF 2 INSULIN-DEPENDENT DIABETES (IDD) GENES TO THE IDD10REGION ON MOUSE-CHROMOSOME-3

Multiple genes control the development of autoimmune diabetes both in humans and in the nonobese diabetic (NOD) strain of mouse. Previously, three insulin-dependent diabetes (Idd) genes, Idd3, Idd10, and Idd17, were localized to mouse Chromosome (Chr) 3. The B10- or B6-derived re sistance alleles at Idd10 and Idd3 together provide the NOD mouse with nearly complete protection from diabetes. In the present study, the 1 0.2-cM region encoding Idd10 was defined further with newly developed congenic strains. A locus, located in the centromeric 2.1 cM of the 10 .2 cM region, contributed to the Idd10 trait. However, this locus did not account for the full effect of Idd10, suggesting the presence of a second gene in the distal portion of the 10.2-cM region. This second gene is designated as Idd18 and is localized to a 5.1-cM region. The r esolution of the originally defined Idd3 locus into at least four sepa rate loci, Idd3, Idd10, Idd17, and Idd18, illustrates the complex poly genic nature of diabetes.