Ornithine Transcarbamylase Deficiency: What is OTC Deficiency

Ornithine transcarbamylase deficiency is a genetic disorder. It is a rare disorder where due to the deficiency of ornithine transcarbamylase enzyme, there is accumulation of ammonia in the blood, giving rise to hyperamonemia.

Ammonia is a toxic byproduct formed in the blood after the breakdown of protein. If ammonia is not excreted and accumulates in the blood, then the consequences are very dangerous.

It affects all the vital organs, liver, kidney and central nervous system.

OTC deficiency is a urea cycle disorder. When protein breaks down, OTC enzyme helps in converting excess of nitrogen into urea in the liver, which is eventually excreted by the kidney. Lack of OTC or deficiency of OTC interrupts the urea cycle, and nitrogen in the form of ammonia cannot get converted to urea. This causes rise in toxic ammonia level.

Ornithine transcarbamylase deficiency can be seen in first few days in an infant. The symptoms are lethargy, not willing to feed, abnormal respiratory rate, and body temperature. Unusual body movements, seizures, and coma proceed in such babies.

In some individuals the symptoms develop later in life, they suffer from mental retardation, delay in development, skin lesions, brittle hair.

Diagnosis is made with the help of blood level of ammonia which is very high. Other parameter is demonstration of orotic acid in urine.


The patient has to discontinue eating protein containing food temporarily and compensate it with carbohydrate and fatty foods.

If the patient is in coma, he may need hemodialysis.

Other medications are used to reduce blood ammonia in an intensive care unit.

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