RESUMO
Cystathionine is well-known intermediate in the metabolism of methionine. It is cleaved to cysteine and homoserine by gamma-cystathionase. This enzyme utilize pyridoxal 5'-phosphate as coenzyme. gamma-cystathionase deficiency leads to persistent excretion of large amount of cystathionine in urine, as well as to accumulation of cystathionine in body tissues and fluids. It is inherited as an autosomal recessive trait and shows wide variety of clinical manifestations. No clinical abnormality seems to be specifically associated with gamma-cystathionase deficiency. The majority of patients responded to high dose administration of pyridoxine. We report the first case of cystathioninuric patient in Korea, 19 months of female with developmental delay. In brain MRI, there was generalized mild brain atrophy. There were several times of brief paroxysmal generalized polyspike and wave discharges in electroencephalography(EEG). In amino acid analysis of urine, there was elevated level of cystathionine. She was treated with high dose of pyridoxine. In follow up analysis of urinary amino acid, the cystathionine level was markedly decreased to normal range, and EEG was normalized. Her development shows improvement.