SAG and congenital stationary night blindness: Oguchi disease (MIM# 613411), a rare form of congenital stationary night blindness (CSNB), results from biallelic variants in either SAG (encoding Arrestin‐1) or GRK1. SAG‐mediated disease is most prevalent in Japanese patients, whilst pathogenic variants in GRK1 are more common in South East Asians.