A genetic explanation for the rising incidence of type 1 diabetes, a polygenic disease.

We had earlier hypothesized, if parents originated from previously isolated populations that had selected against different critical susceptibility genes for a polygenic disease, their offspring could have a greater risk of that disease than either parent. We therefore studied parents of patients with type 1 diabetes (T1D). We found that parents who transmitted HLA-DR3 to HLA-DR3/DR4 patients had different HLA-A allele frequencies on the non-transmitted HLA haplotype than HLA-DR4-transmitters.