General Condition Information
There are no other recognized names for this condition.
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What is Pyruvate carboxylase deficiency
Pyruvate carboxylase deficiency is an inherited (genetic) condition that prevents the body from completing several important processes.
Pyruvate carboxylase helps the body make glucose, a sugar the body uses for energy. It also helps remove lactic acid and ammonia from the body. Lactic acid and ammonia are waste products produced when the body breaks down sugars and protein. And, it helps make myelin and neurotransmitters, which help send signals from the body to the brain.
There are three types of Pyruvate carboxylase deficiency – type A, type B, and type C – that differ in signs, symptoms, and age of onset. We do not fully understand what causes the different types of Pyruvate carboxylase deficiency.
Without enough glucose, myelin, and neurotransmitters, the body cannot make enough energy and cannot send nerve signals throughout the body. Lactic acid and ammonia also build up to toxic levels and can damage the body. This leads to the signs and symptoms of the condition.
Newborn Screening and Follow-Up
Newborn screening for Pyruvate carboxylase deficiency I requires collecting a small amount of blood from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
Screening measures how much of a substance called citrulline is in your baby’s blood. Babies with high levels of citrulline might have Pyruvate carboxylase deficiency.
If your baby’s blood spot screening result for pyruvate carboxylase deficiency 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/or urine tests
- Genetic testing using a blood sample
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems very soon after birth if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition can happen. Screening samples collected too early (before the baby is 24 hours old) may affect the results of screening. Babies with other conditions that have elevated citrulline may also be detected through this screening. An example of another condition that may be detected is Citrullinemia, Type I.
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 Pyruvate carboxylase deficiency type A and type B often appear shortly after birth (within a few days of birth). Babies with Pyruvate carboxylase deficiency type C may not show signs until childhood.
Signs of the condition may include the following:
- Growing slowly or gaining weight slowly (failure to thrive)
- Low blood sugar levels (hypoglycemia)
- High blood ammonia levels (hyperammonemia)
- Rapid breathing (tachypnea)
- Low muscle tone (hypotonia)
- Trouble feeding
- Unusual eye movements (nystagmus)
- Developmental delay
- Birth defects of the brain or brain injuries that happen before the baby is born
- Loss of the white matter in the brain
The condition is caused by a change in the PC gene. This gene gives your body instructions for making the enzyme pyruvate carboxylase. This enzyme helps with several important processes in the body. Without a working PC gene, your baby cannot make enough working enzyme. They may have trouble making glucose, myelin, and neurotransmitters or getting rid of lactic acid and ammonia.
- Pyruvate carboxylase deficiency is an autosomal recessive condition. Babies inherit it when each parent passes down a nonworking PC gene to their baby. Only babies with two nonworking PC genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the PC 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 PC gene, they have a 1 in 4 chance of having a child with Pyruvate carboxylase deficiency.
- Carriers for Pyruvate carboxylase deficiency 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 Pyruvate carboxylase deficiency.
- Parents who already have a child with Pyruvate carboxylase deficiency still have a 1 in 4 chance of having another child with Pyruvate carboxylase deficiency. 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 how to best care for your baby. Currently, the treatment options available cannot stop the progression of the condition. Health care providers will develop a plan that is tailored to the needs of each child.