OAT and Atrophy: Ornithine aminotransferase (OAT) (EC 2.6.1.13) deficiency that causes gyrate atrophy of the choroid and retina (GACR, MIM# 258870) is one of the diseases, which are caused by a deficiency of a protein predominantly expressed within the hepatocytes and therefore to achieve clinically relevant benefit hepatocyte protein expression needs to be restored.