Evidence of genetic epistasis in autoimmune diabetes susceptibility revealed by mouse congenic sublines

AbstractSusceptibility to autoimmune diabetes is a complex genetic trait. Linkage analyses exploiting the NOD mouse, which spontaneously develops autoimmune diabetes, have proved to be a useful tool for the characterization of some of these traits. In a linkage analysis using 3A9 TCR transgenic mice on both B10.BR and NOD.H2k backgrounds, we previously determined that both theIdd2 andIdd13 loci were linked to the proportion of immunoregulatory CD4-CD8- double negative (DN) T cells. In addition toIdd2 andIdd13, five other loci showed weak linkage to the proportion of DN T cells. Of interest, in an interim analysis, a locus on chromosome 12 is linked to DN T cell proportion in both the spleen and the lymph nodes. To determine the impact of this locus on DN T cells, we generated two congenic sublines, which we named Chr12P and Chr12D for proximal and distal, respectively. While 3A9 TCR:insHEL NOD.H2k-Chr12D mice were protected from diabetes, 3A9 TCR:insHEL NOD.H2k-Chr12P showed an increase in diabetes incidence. Yet, the proportion of DN T cells was similar to the parental 3A9 TCR NOD.H2k strain for both of these congenic sublines. A genome-wide two dimensional LOD score analysis reveals genetic epistasis between chromosome 12 and theIdd13 locus. Altogether, this study identified further complex genetic interactions in defining the proportion of DN T cells, along with evidence of genetic epistasis within a locus on chromosome 12 influencing autoimmune susceptibility.
Source: Immunogenetics - Category: Genetics & Stem Cells Source Type: research