Propionic Acidemia, PCCA Related

Gene : PCCA

What is Propionic Acidemia?

Propionic acidemia (PA) is a rare inherited disorder caused by deficiency of the enzyme propionyl-CoA carboxylase. Deficiency of the propionyl-CoA carboxylase enzyme results in a buildup of potentially harmful compounds. High levels of these compounds are toxic to the body and damage the brain and nervous system. Children affected by neonatal-onset PA appear normal at birth but soon develop lethargy, seizures, coma, and possibly death in the first week of life. As they continue to grow, these individuals will have growth deficits, intellectual disability, seizures, brain abnormalities, heart manifestations, and pancreatitis. Individuals affected by late-onset PA have developmental regression, chronic vomiting, low muscle tone, and heart defects. These symptoms may become more pronounced during times of stress caused by illness, injury or long periods without food and are accompanied by breathing problems, seizures, and irritability. Movement disorders are common. Rarely, individuals present only with heart defects and arrhythmia. Currently there is no cure for PA; however initiation of a low-protein diet and medical formula as soon as a diagnosis is made, as well as careful management in times of illness or injury and avoidance of going a long time without food can help to minimize the stress and damage to the brain. Liver transplant is an option for some individuals with PA to treat some symptoms, but there are risks associated with this procedure. PA is caused by pathogenic variants in the PCCA or PCCB genes.

How is propionic acidemia inherited?

PA is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for PA. However, the risk to have a child affected with PA is increased. Testing of reproductive partners is recommended for carriers of PA.

How common is propionic acidemia?

Propionic acidemia is a rare condition that affects all ethnicities. Propionic acidemia is estimated to affect between 1 in 50,000 and 1 in 100,000 newborns worldwide. It is much more common in the Greenland Inuit population, affecting 1 in 1000 newborns and in Saudi Arabia, affecting 1 in 2000 to 5000 newborns.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems





GI Tract


Carrier Rates
Detection Rate
Carrier Frequency
General Population 80% 1 in 158

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