IFIH1 and type 1 diabetes mellitus: From the innate arm of the immune system, variant alleles of the T1-IFN receptor downstream signaling protein Tyk2, the cytosolic viral RNA sensor IFIH1 (MDA5), the macrophage lysosomal enzyme cathepsin H, and the phosphatase SH2B3 are also associated with risk for T1D (Table 1).