Although the Idd9 region does not overlap with any known human T1D susceptibility loci, it contains several genes of immunological significance and genes with variations linked to other human diseases (e.g., genes encoding Lck, MTOR, MASP2, and CD137) (Hildebrandt et al. 2009; Pu et al. 2011; Sorensen et al. 2005). This evidence concerns the gene TNFRSF9 and type 1 diabetes mellitus.