N-acetylaspartic aciduria due to aspartoacylase deficiency--a new aetiology of childhood leukodystrophy.

We describe a male infant with psychomotor retardation and leukodystrophy who excretes large quantities of N-acetylaspartate in his urine. A high CSF/plasma concentration ratio of N-acetylaspartate indicates that this substance originates in the brain. Fibroblasts from the patient are deficient in aspartoacylase activity. It is proposed that the dysmyelination in the patient may be due to failure of N-acetylaspartate to serve as a carrier of acetyl groups from mitochondria to the cytosol for lipogenesis.