Late diagnosis of ornithine transcarbamylase defect in three related female patients: polymorphic presentations.

OBJECTIVE: To describe three female patients of one family with different phenotypes of the same mutation of the ornithine transcarbamylase gene. X-linked inherited ornithine transcarbamylase deficiency is the most frequent urea cycle disorder. Many of the hemizygous males die during the neonatal period. Women, who are mostly healthy carriers, can also develop symptomatic hyperammonemia.

DESIGN: Case study.

SETTING: Intensive care unit and internal medicine unit at a university hospital.

PATIENTS: The 20-yr-old female propositus was hospitalized for unexplained coma. She had a history of headaches, recurrent vomiting, specific anorexia for high-protein foods, and an acute neurologic crisis with alleged food poisoning 8 yrs before. The present episode began with psychiatric symptoms and seizures treated by diazepam and valproate. This unexplained coma, associated with respiratory alkalosis and major brain swelling on brain computed tomography scan, revealed hyperammonemia leading to the diagnosis of ornithine transcarbamylase deficiency. Continuous venovenous hemodiafiltration and treatment with sodium benzoate and phenylbutyrate improved the situation. However, the patient had some neurologic sequelae. DNA studies have disclosed a pathogenic mutation in the ornithine transcarbamylase gene of the patient, her mother, and her sister. For the mother, the disease was overlooked despite the onset of unusual headaches and neurologic signs that mimicked a cerebral tumor 12 yrs before. The 28-yr-old sister of the propositus has always been asymptomatic, even during pregnancy.

CONCLUSIONS: Diagnosis of urea cycle disorder should be considered in any patient with unexplained neurologic and psychiatric disorders with selective anorexia, even in adulthood. Unexplained coma with cerebral edema and respiratory alkalosis requires urgent measurement of ammonemia and metabolic work-up.