ExtractW e have described a patient with ornithine transcarbamylase (OTC) deficiency.T h e clinical course and pedigree substantiate the X-linked transmission of the defect with varying degrees of illness in females. Because orotic aciduria accompanied hyperammonemia in the patient, orotic acid was measured as an indication of a partial OTC deficiency after ammonia and protein loading in members of the patient's family. Both the mother, a n obligate carrier, and an aunt, the only symptomatic female in this pedigree, had hyperammonemia after the ingestion of ammonium chloride. They also had significant orotic aciduria after a protein load as did the two female cousins whose ammonium tolerance was normal. T h e maternal grandmother excreted a large amount of orotic acid in her urine relatively consistently. 'These data suggest that the two female cousins and the maternal grandmother are asymptomatic female heterozygotes despite their normal ammonium loading tests. SpeculationProtein loading in the form of a relatively palatable and innocuous meal, followed by determination of orotic acid content in urine, may prove to be a sensitive, noninvasive, and easy means to identify female carriers of ornithine transcarbamylase deficiency.

No abstract

No abstract

No abstract