KCNJ13 and vitreoretinal degeneration: Mutations in the inwardly rectifying potassium channel gene KCNJ13 have been shown to cause both snowflake vitreoretinal degeneration (SVD) (Hejtmancik et al., 2008) and Leber congenital amaurosis (LCA) (Sergouniotis et al., 2011).