Brain creatine depletion: Guanidinoacetate methyltransferase deficiency (improving with creatine supplementation)

The authors describe an Italian child with guanidinoacetate methyltransfera se deficiency, neurologic regression, movement disorders, and epilepsy duri ng the first year of life. Brain MRI showed pallidal and periaqueductal alt erations. In vivo H-1-MRS showed brain creatine depletion. The assessment o f guanidinoacetic acid concentration in biologic fluids confirmed the diagn osis. Clinical, biochemical, and neuroradiologic improvement followed creat ine supplementation.