Since Tyk2 gene KO mice were highly susceptible to EMC-D virus-induced diabetes as described above, we screened for mutations of the Tyk2 gene in virus-induced diabetes-sensitive DBA/2J (DBA), SJL/J (SJL) and SWR/J (SWR) mice as well as resistant B6, C3H/HeJ and moderately susceptible A/J, and BALB/cJ mice. The gene discussed is TYK2; the disease is diabetes mellitus.