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.