RT Book, Section A1 Schulze, Andreas A1 Braissant, Olivier A2 Sarafoglou, Kyriakie A2 Hoffmann, Georg F. A2 Roth, Karl S. SR Print(0) ID 1140315802 T1 Creatine Deficiency Syndromes T2 Pediatric Endocrinology and Inborn Errors of Metabolism, 2e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9780071773140 LK accesspediatrics.mhmedical.com/content.aspx?aid=1140315802 RD 2024/03/29 AB Hereditary defects of creatine (Cr) synthesis or transport of Cr are described as Cr deficiency syndromes (CDSs).1 The group of CDSs consists of three different diseases: arginine:glycine amidinotransferase (AGAT), guanidinoacetate methyltransferase (GAMT), and Cr transporter (CrT) deficiency. They essentially affect the brain, where their common denominator is the virtually complete absence of Cr and phosphocreatine (PCr) when measured by magnetic resonance spectroscopy (MRS). Gyrate atrophy of choroid and retina represents an additional condition that may be added on to the CDSs because Cr deficiency is part of its clinical consequences.