X-linked Creatine Transporter Deficiency (CTD, SLC6A8 Deficiency, CRTR) is a mutation in the creatine transporter gene SLC6A8. This results in a blockage in the transportation of creatine to the brain and muscles.
To date, there is no proven treatment for CTD. It is estimated that Creatine Transporter Deficiency (CTD) is the second largest cause of x-linked mental disability behind Fragile X syndrome.