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PCCA gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

PCCA gene

The PCCA gene provides instructions for creating the alpha subunit of the propionyl-CoA carboxylase enzyme, which is critical for the breakdown of proteins and fats.

Normal Function

The PCCA gene provides instructions for making the alpha subunit of the enzyme propionyl-CoA carboxylase. Six alpha subunits combine with six beta subunits (produced by the PCCB gene) to form a functional enzyme. The alpha subunit also contains a region for binding to the B vitamin biotin.

This enzyme is essential for the normal processing of proteins and fats. It helps break down specific amino acids (isoleucine, methionine, threonine, and valine), as well as certain lipids and cholesterol. It converts propionyl-CoA into methylmalonyl-CoA, which is then further broken down to produce energy.

Health Conditions Related to Genetic Changes

Propionic acidemia

More than 120 mutations in the PCCA gene have been identified in people with propionic acidemia, a condition that causes severe health problems shortly after birth. The impact of these mutations includes:

  • Loss of function: Mutations prevent the production of functional propionyl-CoA carboxylase or significantly reduce its activity.
  • Toxic buildup: Because the enzyme cannot properly process certain proteins and lipids, propionyl-CoA and other harmful compounds accumulate to toxic levels.
  • Systemic damage: The buildup of these toxic compounds damages the brain and nervous system, leading to the serious health complications associated with the condition.

Frequently Asked Questions

Newborns with propionic acidemia often appear normal at birth but develop severe symptoms within days or weeks. Initial signs can include poor feeding, vomiting, lethargy, weak muscle tone (hypotonia), and seizures. As toxic compounds build up, infants may experience rapid breathing, unusual odors (like "sweaty feet"), and coma. Parents should seek immediate emergency medical attention if an infant exhibits any of these symptoms, as prompt treatment is critical to prevent severe brain damage or death.
Propionic acidemia is often diagnosed through routine newborn screening programs in many countries, which detect elevated levels of propionylcarnitine in blood spots. If screening is positive, further diagnostic tests include urine organic acid analysis (looking for propionic acid and its derivatives) and plasma amino acid analysis. Definitive diagnosis is confirmed by measuring propionyl-CoA carboxylase enzyme activity in cells or by genetic testing of the PCCA and PCCB genes.
Management primarily involves a strict, lifelong diet severely restricted in specific proteins (isoleucine, methionine, threonine, and valine) and certain fats. This often requires specialized medical formulas and careful monitoring by a metabolic dietitian. Medications may include carnitine to help remove toxic metabolites and antibiotics to reduce propionate-producing bacteria in the gut. During metabolic crises, intravenous fluids, glucose, and sometimes hemodialysis are used to rapidly reduce toxic levels.
Propionic acidemia is inherited in an autosomal recessive pattern. This means that a child must inherit two copies of a mutated PCCA (or PCCB) gene, one from each parent, to develop the condition. If both parents are carriers (meaning they each have one normal and one mutated gene), there is a 25% chance with each pregnancy that their child will inherit two mutated genes and be affected, a 50% chance the child will be a carrier, and a 25% chance the child will inherit two normal genes.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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