Recently, based on the discovery of natural mutations of TYK2 gene as murine encephalomyocarditis (EMC)-D virus-induced diabetes susceptibility gene causing deteriorated type 1 interferon (IFN) response (Izumi et al., 2015), we could show that “TYK2 promoter variant” in Japanese subjects is associated with an increased risk of T1D (Nagafuchi et al., 2015). The gene discussed is TYK2; the disease is diabetes mellitus.