Severe epilepsy in X-linked creatine transporter defect (CRTR-D).

Disorders of creatine synthesis or its transporter resulting in neurological impairment with mental retardation and epilepsy have only been recognized in recent years. To date, the epileptic disorder observed in creatine transporter deficiency (CRTR-D) has been described as a mild phenotype with infrequent seizures and favorable response to common antiepileptic drugs. We report on a 5 year-old boy with known speech delay who presented with severe and refractory epilepsy. After extensive investigations, metabolite analysis and brain 1H-MRS suggested CRTR-D, which was confirmed by the detection of a known pathogenic mutation in the SLC6A8 gene (c.1631C>T; p.Pro544Leu).