Creatine Transporter Deficiency (CTD) is an inborn error of creatine metabolism in which creatine is not properly transported to the brain and muscles due to defective creatine transporters. CTD is an X-linked disorder caused by in SLC6A8. SLC6A8 is located at Xq28. Hemizygous males with CTD express speech and behavior abnormalities, intellectual disabilities, development delay, seizures, and autistic behavior. Heterozygous females with CTD generally express fewer, less severe symptoms. CTD is one of three different types of cerebral creatine deficiency (CCD). The other two types of CCD are guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency. Clinical presentation of CTD is similar to that of GAMT and AGAT deficiency. CTD was fi