Hyperammonemia due to NAGS deficiency

Overview

Hyperammonemia due to N-Acetylglutamate synthase (NAGS) deficiency is a metabolic disturbance characterised by an excess amount of ammonia in the blood. Children with this severe urea cycle disorders typically show symptoms directly after the first 24 hours of life. Symptoms may include vomiting, lethargy, seizures, respiratory distress and coma. The basic tests to make the diagnosis are the measurement of blood ammonia, plasma amino acids and urine organic acids concentrations. Severe consequences can be avoided through direct medication in combination with a strict diet.


Synonyms: Type I Hyperammonemia, Hyperammonemia due to N-Acetylglutamate synthase deficiency; N-Acetylglutamate Synthetase Deficiency


Sources: Wikipedia, National Urea Cycle Disorders Foundation, Medscape

Symptoms Hide

Children with severe urea cycle disorders typically show symptoms after the first 24 hours of life. The baby may be irritable at first, or refuse feedings, followed by vomiting and increasing lethargy. Soon after, seizures, hypotonia (poor muscle tone, floppiness), respiratory distress (respiratory alkalosis), and coma may occur. These symptoms are caused by rising ammonia levels in the blood (hyperammonemia). Sepsis and Reye’s syndrome are common misdiagnoses. If untreated, these severely affected infants will die.

Major characteristics of NAGS deficiency, considered the rarest urea cycle disorder, include severe hyperammonemia, deep encephalopathy despite only mild hyperammonemia, recurrent diarrhea and acidosis, movement disorder, hypoglycemia and hyperornithinemia. Hyperammonemia due to NAGS deficiency is a severe neonatal disorder with fatal consequences, if not detected immediately upon birth.

Sources: Wikipedia, National Urea Cycle Disorders Foundation, Medscape

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