Creatine Transporter Deficiency in Two Brothers with Autism Spectrum Disorder.

BACKGROUND: Creatine transporter deficiency (CTD) is a treatable, X-linked, inborn error of metabolism.

CASE CHARACTERISTICS: Two brothers with autism spectrum disorder were diagnosed with CTD at the ages of 17 and 12 years. Both were found to have a previously reported hemizygous p.408delF (c.1216_1218delTTC) deletion mutation.

OUTCOME: Both patients were given creatine monohydrate, L-arginine, L-glycine and S-adenosylmethionine, which partially improved the behavioral problems.

MESSAGE: Serum creatinine levels, creatine peak at brain MR spectroscopy or creatine/creatinine ratio in urine should be evaluated to identify CTD in children with autistic behavior and language disorders.