General Condition Information
- Isovaleric acidemia (isovaleryl-CoA dehydrogenase)
- Isovaleryl CoA dehydrogenase deficiency
It is estimated that less than 20 babies are born each year with this condition in the United States.
What is Isovaleric acidemia
Isovaleric acidemia is an inherited (genetic) condition that prevents the body from breaking down certain proteins.
Isovaleric acidemia is caused by unusually low levels of isovaleryl CoA dehydrogenase. Isovaleryl CoA dehydrogenase is the name of an enzyme in your body that helps you digest a part of some proteins called leucine.
If the isovaleryl CoA dehydrogenase your baby has does not work well, they will have trouble breaking down proteins containing leucine. This condition can be more or less severe depending on how well your baby’s enzyme works. The acute form is more severe, and the chronic/intermittent form is less severe.
Waste, including toxins, can build up when the body does not process proteins. Toxins that are acids cause your blood to become acidic. Acidic blood is called acidemia. These toxins can damage your baby’s brain and nerves. If untreated, this damage leads to the signs and symptoms of the condition.
Newborn Screening and Follow-Up
Newborn screening for isovaleric 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 food. Babies with high levels of these substances might have isovaleric acidemia.
If your baby’s blood spot screening result for isovaleric 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/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 soon after birth if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition are rare.
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 isovaleric acidemia often appear in the first two weeks after birth. In chronic/intermittent isovaleric acidemia, signs may not appear until later in infancy or childhood and are usually less severe.
Signs of the condition may include the following:
The condition is caused by a change in the IVD gene. This gene gives the body instructions for making isovaleryl CoA dehydrogenase. This enzyme is required for your body to break down a part of some proteins called leucine.
Without a working IVD gene, your baby’s body cannot make an enzyme that works well enough to properly break down leucine. As a result, acidic toxins build up in their body.
- Isovaleric acidemia is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking IVD gene to their baby. Only babies with two nonworking IVD genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the IVD 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 IVD gene, they have a 1 in 4 chance of having a child with isovaleric acidemia.
- Carriers for isovaleric 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 isovaleric acidemia.
- Parents who already have a child with isovaleric acidemia still have a 1 in 4 chance of having another child with isovaleric 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:
- Frequent feedings to avoid long periods without food
- Glycine supplements
- L-carnitine supplements
- Diet of special formulas or foods in some cases
Children who receive early and ongoing treatment for isovaleric acidemia can have healthy growth and development.