A male infant of six weeks of age exhibited symptoms of pronounced hyperammonemi

Question

A male infant of six weeks of age exhibited symptoms of pronounced hyperammonemia, which included vomiting, fever, irritability, and screaming episodes interspersed with periods of lethargy. The infant had low levels of blood urea, elevated serum transaminase, generalized hyperaminoacidemis and aminoaciduria. The levels of citrulline, arginosuccinic acid, and arginine were relatively low in both blood and urine. Enzymatic analysis of liver tissue identified one enzyme of the urea cycle with approximately 20% of normal activity and the enzyme was active only in the presence of relatively high concentrations of N-acteylglutamate. The infant was treated with a supplement containing arginine, pyridoxine, and alpha-keto analogs of essential amino acids. As part of the therapy, dietary protein was also restricted and the parents were told to ensure the child is fed every 4 hours or so. Which enzyme is deficient? Why were blood levels of ammonia high in this infant? Explain why Infants with this enzyme deficiency normally exhibit relatively low levels of citrulline, arginosuccinic acid, arginine and urea. Why is administration of supplemental arginine recommended for this infant? Why were pyridoxine and alpha-keto analogs of essential amino acids administered? Why was dietary protein restricted and the child kept in a fed state? Why would you expect to see elevated concentrations of glutamate? glutamine and alanine in the blood and urine of this Infant? Briefly explain the normal function of these proteins and the effect Below are five defects. Briefly explain the normal function of these proteins and the effect.

Explanation / Answer

1. Hyperammonemia is a metabolic disturbance having an excess of ammonia in the blood.

A. It is characterized by the reduced activity of any of the enzymes in the urea cycle, mostly by ornithine transcarbamylase deficieny (OTCD).

B. Ammonia level in the blood rises when the liver cannot convert ammonia to urea, otherwise it is converted into urea, which is eliminated through urine.

C. The child is treated so because dietary protein is not allowed which is a metabolic source of ammonium.

D. It is so because ornithine transcarbamylase is the final enzyme in the urea cycle which are responsible for producing them.

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