Asparagine synthetase deficiency: clinical features and experience with asparagine supplementation.

ASNSD should be suspected in patients with progressive microcephaly and early-onset epilepsy despite normal metabolic screening, and CSF amino acid analysis is valuable for diagnosis.

Although a reduction in seizure frequency was observed following L-asparagine supplementation in our patient, this finding should be interpreted cautiously because phenobarbital was discontinued and topiramate therapy was initiated during the same period.