Analysis of chromosome 6q in Basque families with type 1 diabetes

Over the last few years several studies of linkage between non-HLA loci and type 1 diabetes mellitus have mapped several putative susceptibility genes on chromosome 6q; in fact, positive evidence of linkage and/or association of IDDM5 (6q25). IDDM8 (6q27) and IDDM15 (6q21) with type 1 diabetes has b een reported. We have studied these loci in diabetic families of Basque ori gin, a genetically homogeneous population, to avoid artifactual association results due to admixture within the sample analysed. Statistical analyses of linkage were per formed using a transmission disequilibrium test (TDT). We could not confirm linkage for IDDM5, IDDM8 and IDDM15 in our population, possibly due to population-specific differences in genetic susceptibility and/or environmental triggering factors to type 1 diabetes.