General Condition Information
- Propionic acidemia (propionyl-CoA carboxylase)
- Propionyl CoA carboxylase deficiency
- Proprionic acidemia
- Over 30 babies are born with this condition every year in the United States.
- It is more common in the Inuit of Greenland, some Amish communities, and in the Middle East.
- Visit GeneReviews to learn more about how often this condition occurs.
What is Propionic acidemia
Propionic acidemia is an inherited (genetic) condition that prevents the body from breaking down certain proteins, fats, and cholesterol. Breaking down proteins and processing fats is very important for your body to work properly.
In propionic acidemia, an enzyme called propionyl-CoA carboxylase does not work correctly. This enzyme helps digest certain proteins, fats, and cholesterol so that your body can either use or get rid of them.
Without enough functioning propionyl-CoA carboxylase enzyme, your baby will have trouble making energy and getting rid of waste. This condition can be more or less severe depending on how well this enzyme works in your baby’s body.
When your baby cannot break down waste, toxins can build up. When these toxins are acids, your baby’s blood can become acidic. Acidic blood is called acidemia. If untreated, acidemia can cause brain damage that leads to the signs and symptoms of the condition. In severe cases, this condition can result in coma or death unless treated early.
Newborn Screening and Follow-Up
Newborn screening for propionic acidemia is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
During screening, a special machine measures how much of certain substances (called acylcarnitines) are in your baby’s blood. Your body produces these substances when it breaks down fats. A specific organic acid (called methylcitric acid) may also be measured. Babies with high levels of these substances might have propionic acidemia.
If your baby’s blood spot screening result for propionic acidemia is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood and urine tests
- Genetic testing using a blood sample
- Small skin sample
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have very serious health problems in the first few days of life if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition can happen. Some situations can affect screening results:
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
Signs of propionic acidemia can vary widely, but in most cases, health problems develop within the first few days of life. They can be triggered by eating foods that the body cannot break down or by going long periods without eating. Symptoms can also be brought on by illness or infection. Milder forms of propionic acidemia may not appear until later in childhood.
Signs of the condition may include the following:
Propionic acidemia is caused by a change in the PCCA or PCCB gene. These genes give your body instructions for making the enzyme propionyl-CoA carboxylase. This enzyme helps break down proteins, fats, and cholesterol.
Without a working PCCA or PCCB gene, your baby cannot make enough working propionyl-CoA carboxylase to break down these substances. As a result, harmful toxins build up in the body.
- Propionic acidemia is an autosomal recessive condition. Babies inherit the condition when each parent passes down the same nonworking gene that causes propionic acidemia (PCCA or PCCB) to their baby. Only babies with two matching nonworking genes—for example, one nonworking PCCA from the mom and one nonworking PCCA from the dad—have this condition. Babies with two nonworking genes that do not match—for example, one nonworking PCCA from the mom and one nonworking PCCB from the dad—will not have this condition.
- People with one working copy and one nonworking copy of the PCCA or PCCB gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the PCCA or PCCB gene, they have a 1 in 4 chance of having a child with propionic acidemia.
- Carriers for propionic acidemia often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with propionic acidemia.
- Parents who already have a child with propionic acidemia still have a 1 in 4 chance of having another child with propionic acidemia. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.
Treatments may include the following:
- Diet low in certain proteins and fats
- Special formulas and foods
- Regular and frequent meals and snacks
- Biotin and carnitine supplementation in some cases
- Antibiotics in some cases
Early and ongoing treatment for propionic acidemia can help reduce and prevent some of the early signs and symptoms. Even with treatment, some children might still have developmental delays or learning difficulties.