D-amino acids (DAAs) such as D-serine and D-alanine are agonists of the glycine subunit and have shown promise as adjunctive therapies for the treatment of schizophrenia.6 However, the oxidation of DAAs by the flavoenzyme D-amino acid oxidase (DAAO) limits their use in treatment.7,8 Oxidation reduces their bioavailability and increases products that are potentially nephrotoxic in high dosages.9,10. The gene discussed is DAO; the disease is schizophrenia.