Type II citrullinemia associated with neutropenia.

A 37-year-old Japanese man was admitted with delirium and hyperammonemia. He was diagnosed as having type II citrullinemia because of an elevated citrulline level on amino acid analysis and very low hepatic argininosuccinate synthetase activity. He also showed a low neutrophil count and a low serum level of granulocyte colony-stimulating factor. Reduced production of this cytokine and/or impairment of its feedback regulation by the neutrophil count may have played a role in the neutropenia of this patient.