OTC deficiency

Ornithine Transcarbamylase Deficiency Ornithine Transcarbamylase Deficiency (OTC deficiency) is a rare genetic disorder that affects the urea cycle, a series of biochemical reactions that occur in the liver. This cycle is responsible for removing ammonia from the bloodstream. Ammonia is a waste product of protein metabolism and is toxic if it accumulates in the body.

Overview

OTC deficiency is an X-linked genetic disorder, meaning it is caused by mutations in the OTC gene located on the X chromosome. This condition primarily affects males, although females can be carriers and may exhibit mild symptoms.

Symptoms

The symptoms of OTC deficiency can vary widely depending on the severity of the enzyme deficiency. Common symptoms include:

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

In severe cases, especially in newborns, the condition can lead to life-threatening complications if not treated promptly.

Diagnosis

Diagnosis of OTC deficiency typically involves:

• Blood tests to measure ammonia levels
• Genetic testing to identify mutations in the OTC gene
• Liver function tests

Treatment

Treatment for OTC deficiency focuses on managing symptoms and preventing hyperammonemia. This may include:

• Dietary restrictions to limit protein intake
• Medications such as sodium phenylbutyrate or sodium benzoate to help remove ammonia from the body
• Liver transplantation in severe cases

Genetics

OTC deficiency is inherited in an X-linked recessive pattern. Males with a mutation in the OTC gene will express the disease, while females with one mutated copy of the gene are typically carriers and may have mild symptoms.

Prognosis

The prognosis for individuals with OTC deficiency varies. Early diagnosis and treatment are crucial for preventing severe complications. With proper management, individuals can lead relatively normal lives, although they may need to adhere to dietary restrictions and medication regimens.

Research

Ongoing research into OTC deficiency includes:

• Gene therapy approaches to correct the underlying genetic defect
• New medications to better manage ammonia levels
• Improved diagnostic techniques

See Also

• Urea cycle disorders
• Hyperammonemia
• Genetic disorders

External Links

• National Organization for Rare Disorders
• Genetic and Rare Diseases Information Center

NIH genetic and rare disease info

• NIH info on OTC deficiency

OTC deficiency is a rare disease.