In order to investigate further the pathophysiological role of KCNJ13 mutations in snowflake vitreoretinal degeneration (SVD, MIM 193230) and Leber congenital amaurosis (LCA16, MIM 614186) a knockout mouse model was constructed by inserting a gene trap cassette in intron 1, which consisted of a splice accepter (SA) followed by IRES and beta galactosidase sequences. The gene discussed is KCNJ13; the disease is vitreoretinal degeneration.