The clinical syndrome of creatine transporter deficiency.

To describe the clinical, spectroscopic and neuropsychological features of the first family diagnosed with a defect in the creatine transporter. Proton Magnetic Resonance Spectroscopy (MRS) indicated an absence of creatine and phosphocreatine in the brain of a male patient characterized by developmental delay, mild epilepsy and severe expressive language impairment. Subsequent genetic testing revealed a defect in the X-linked creatine transporter (SLC6A8/CT1), with a hemizygous mutation in the patient and a heterozygous mutation for the female carriers. Magnetic resonance imaging and spectroscopy examinations were performed on a 1.5T clinical MR Scanner. Neuropsychological examinations were performed on the index patient and maternal relatives. Preliminary spectroscopy results indicate the disorder prevents transport of creatine and phosphocreatine in the brain of the affected male. However, the skeletal muscle demonstrates the presence of creatine and phosphocreatine which correlates clinically with normal structure and function. Female carriers demonstrated impairments in confrontational naming and verbal memory assessments. This new neurological syndrome is associated with developmental delay, mild epilepsy, severe language impairment. MR Spectroscopy is a non-invasive method for obtaining a preliminary diagnosis of this disorder. Muscle creatine uptake may be normal in this disorder.