To investigate the role of MDA5 in T1D, we generated an in-frame deletion within the helicase 1 domain of MDA5 (Ifih1ΔHel1) and an out-of-frame deletion (Ifih1KO) in NOD mice with zinc finger nuclease–mediated (ZFN-mediated) gene targeting (61). This evidence concerns the gene IFIH1 and type 1 diabetes mellitus.