OAT and Gyrate atrophy of choroid and retina: Mutations in the ornithine aminotransferase gene (OAT) cause gyrate atrophy (GA) (OMIM 258870), which is characterized by increased ornithine serum levels and has a similar clinical phenotype to CHM, with patients presenting with night blindness and progressive chorioretinal atrophy, eventually leading to blindness (58).