Our findings are consistent with the slow peripheral retinal degeneration observed in mice with a Mertk missense mutation generated by ENU mutagenesis on a B6 background [35], and indicate that a widely available line of Mertk knockout mice is hypomorphic for Tyro3 due to reduced expression from a tightly linked Tyro3129 allele. Here, MERTK is linked to retinal degeneration.