clinical differential diagnosisthe organic acidemias are important in the differential diagnosis of metabolic and neurologic derangement in the neonate and of new-onset neurologic signs in the older child. a-organic aciduriaseveral disorders, not classified as primary disorders of organic acid metabolism, have a characteristic urinary organic acid profile that suggests the appropriate diagnosis...

Long-term correction of urea cycle disorders is achieved by correction of the enzymatic defect in hepatocytes. Currently, orthotopic liver transplantation is the primary means of achieving this correction. In the United States most liver transplantations for urea cycle disorders have been restricted to patients with ornithine transcarbamylase deficiency and argininosuccinic aciduria. However, p...

Ornithine transcarbamylase deficiency is an X-linked disorder of the urea cycle that can cause hyperammonemic encephalopathy in hemizygous males and heterozygous females. Affected females typically limit protein intake in their diet. This case report describes a 36-year-old woman with ulcerative colitis who went into hyperammonemic coma after administration of total parenteral nutrition. A simi...

Urea cycle disorders are incurable enzymopathies that affect nitrogen metabolism and typically lead to hyperammonemia. Arginase deficiency results from a mutation in Arg1, the enzyme regulating the final step of ureagenesis and typically results in developmental disabilities, seizures, spastic diplegia, and sometimes death. Current medical treatments for urea cycle disorders are only marginally...

Most inborn errors of intermediary metabolism presenting in the neonatal period fall schematically into three clinical categories: (1) those which lead to a neurological distress 'intoxication type' with a symptom-free interval, vomiting, comas, hypertonia, abnormal movements and frequent humoral disturbances (organic acidaemias, congenital urea cycle defects); (2) those which lead to a neurolo...

Urea cycle defects presenting early in life with hyperammonemia remain difficult to treat and commonly necessitate liver transplantation. Gene therapy has the potential to prevent hyperammonemic episodes while awaiting liver transplantation, and possibly also to avert the need for transplantation altogether. Ornithine transcarbamylase (OTC) deficiency, the most prevalent urea cycle disorder, pr...

Ornithine transcarbamylase (OTC) deficiency is an X-linked urea cycle defect. While hemizygous males typically present with hyperammonemic coma in infancy, reports of rare late-onset presentations exist, with poor outcomes in males up to 58 years old. Relatives with mutations identical to affected patients often remain asymptomatic, and it is likely that environmental and genetic factors influe...

Our study provides novel findings of experimental hypokalemia reducing urea cycle functionality and thereby severely increasing plasma ammonia. This is pathophysiologically interesting because ammonia increases during by a hitherto unknown mechanism, which may be particular important in relation to the unexplained link between hepatic encephalopathy. Potassium deficiency decreases gene expressi...

The omithine cycle [1], also called the urea cycle, is an enzyme system that converts ammonia into urea (for recent reviews, see [2-4]) (Figure 1). Ammonia, which is produced mainly by amino acid metabolism, is toxic to higher animals, and must be excreted or detoxified. Fish and amphibian larvae such as tadpoles excrete ammonia from the gills directly into the surrounding water. Mammalian fetu...