Ornithine carbamoyltransferase deficiency disease

Genetic disorder affecting the urea cycle

Ornithine carbamoyltransferase deficiency
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Synonyms	OTC deficiency
Pronounce
Field	N/A
Symptoms	Hyperammonemia, lethargy, vomiting, seizures
Complications	N/A
Onset	Neonatal or later in life
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the OTC gene
Risks	Family history
Diagnosis	Genetic testing, ammonia levels in blood
Differential diagnosis
Prevention
Treatment	Low-protein diet, ammonia scavenging drugs, liver transplant
Medication
Prognosis	Variable, can be severe if untreated
Frequency	Rare
Deaths

Ornithine carbamoyltransferase deficiency (OTC deficiency) is a rare genetic disorder that affects the urea cycle, a series of biochemical reactions that convert ammonia into urea for excretion from the body. This condition is caused by mutations in the OTC gene, which provides instructions for making the enzyme ornithine carbamoyltransferase. This enzyme is essential for the proper function of the urea cycle.

Symptoms

The symptoms of OTC deficiency can vary widely but often include:

• Hyperammonemia (elevated levels of ammonia in the blood)
• Lethargy
• Vomiting
• Seizures
• Coma in severe cases

Symptoms can present in the neonatal period or later in life, depending on the severity of the enzyme deficiency.

Causes

OTC deficiency is inherited in an X-linked recessive pattern. This means that males are more frequently affected, while females may be carriers and can sometimes exhibit mild symptoms.

Diagnosis

Diagnosis of OTC deficiency typically involves:

• Measuring ammonia levels in the blood
• Genetic testing to identify mutations in the OTC gene
• Liver biopsy to assess enzyme activity (less commonly used now due to advances in genetic testing)

Treatment

Management of OTC deficiency includes:

• A low-protein diet to reduce ammonia production
• Ammonia scavenging drugs such as sodium phenylbutyrate or sodium benzoate
• Liver transplant in severe cases

Prognosis

The prognosis for individuals with OTC deficiency varies. Early diagnosis and treatment are crucial for preventing severe complications and improving outcomes.

Related Pages

• Urea cycle
• Hyperammonemia
• Genetic disorder
• X-linked recessive inheritance
• Liver transplant