GAD1 and diabetes mellitus: Interestingly, TYK2 promoter variant was associated with a significantly higher susceptibility to diabetes in anti-GAD antibody-negative patients (OR, 3.3; P = 0.002), of which observation is consistent with Tyk2 gene mutation dependent murine virus-induced diabetes that simulates non-autoimmune rapid onset and fulminant T1D without autoantibody production (Imagawa et al., 2000, Nagafuchi et al., 2013, Izumi et al., 2015).