Creatine Deficiency Syndromes

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Creatine Deficiency Syndromes – are inborn errors of creatine metabolism and include the two creatine biosynthesis disorders, guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine: glycine amidinotransferase (AGAT) deficiency, and the creatine transporter (CRTR) deficiency. Intellectual disability and seizures are common to all three CDS. The majority of individuals with GAMT deficiency have a behavior disorder that can include autistic behaviors and self-mutilation; about 40% have movement disorder. Onset is between ages three months and three years. Clinically, symptoms in affected males with CRTR deficiency ranges from mild intellectual disability and speech delay to severe intellectual disability, seizures, movement disorder and behavior disorder; age at diagnosis ranges from two to 66 years. Clinical symptoms of females for CRTR deficiency ranges from asymptomatic to severe phenotype resembling male phenotype. Diagnostic testing includes molecular gene testing for GAMT, GATM, and SLC6A8 and cerebral creatine deficiency in brain MR spectroscopy (1H-MRS). Early treatment at the asymptomatic stage of the disease in individuals with GAMT and AGAT deficiencies appears to be beneficial. In those treated with creatine monohydrate, routine measurement of renal function to detect possible creatine-associated nephropathy is warranted.