A Novel Argininosuccinate Synthetase Gene Mutation in a Korean Family with Type I Citrullinemia

Citrullinemia type I is an urea cycle defect caused by mutations in the argininosuccinate synthetase (ASS1) gene.We report a novel argininosuccinate synthetase gene mutation in a Korean family with type I citrullinemia.Metabolic evaluation revealed significant hyperammonemia.Amino acid/acylcarnitine screening using tandem mass spectrometry showed high level of citrulline.Plasma amino acid analysis showed high level of citrulline and the urine organic acid analysis showed makedly increased level of orotic acid.To confirm diagnosis of citrullinemia we did mutation analysis of the ASS1 gene.The patient was found to have mutations of c.689G>C (p.G230A) and c.892G>A (p.E298K), which were new types of argininosuccinate synthetase gene mutation have never been reported in Korea.We report a novel case of argininosuccinate synthetase 1 gene mutation and suggest that the gene study to the family members is necessary to carry out when a patient is diagnosed as citrullinemia.