General Condition Information
Other Names
- Carnitine acyl-carnitine translocase deficiency
- Carnitine acylcarnitine translocase
- Carnitine acylcarnitine translocase deficiency
- Carnitine/acylcarnitine translocase deficiency
- Carnitine: acylcarnitine translocase deficiency
Condition Type
Birth Prevalence
- It is unknown how many babies are born with this rare condition each year in the United States.
- Visit Gene Reviews to learn more about how often this condition occurs.
Screening Finding
What is carnitine-acylcarnitine translocase deficiency
Carnitine-acylcarnitine translocase (CACT) deficiency is an inherited (genetic) condition that prevents the body from breaking down certain fats and turning them into energy.
CACT is a protein in your body that helps with the processing of a type of fat called “long-chain fatty acids.” CACT is a transporter, which is a type of protein that moves substances where they need to go inside your cells.
Without enough working CACT transporter, your baby can have trouble using fats for energy. This condition can be more or less severe depending on how many normal copies of the transporter your baby can make.
Breaking down fat for energy allows your body to work properly. Energy from fat is especially important after a long time without food (fasting) and during illness. If your body does not make enough energy from fat, blood sugar levels can become dangerously low.
When fats are not processed, waste can build up, including toxins. These toxins can cause damage to your liver, heart, and muscles. If untreated, the lack of energy and increased toxins lead to the signs and symptoms of the condition.
Newborn Screening and Follow-Up
Newborn screening for CACT deficiency 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 makes energy from fats. Babies with high levels of these substances might have CACT deficiency.
If your baby’s blood spot screening result for CACT 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
- Small skin 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. Some situations can affect screening results for CACT deficiency:
- Screening samples were collected too early (before the baby is 24 hours old)
- Babies who were given carnitine may have false positive results for this condition.
Condition Details
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 CACT deficiency may appear at different times but usually appear soon after birth. In milder forms of CACT deficiency, signs and symptoms may be triggered by common illnesses (like a cold or flu) or a long time without food.
Signs of the condition may include the following:
- High blood ammonia levels (hyperammonemia)
- Enlarged liver (hepatomegaly)
- Heart problems
- Breathing problems
- Fever
- Diarrhea
- Vomiting
- Seizures
- Low blood sugar (hypoglycemia)
- Floppy arms or legs (hypotonia)
- Behavior changes
- Coma
The condition is caused by a change in the SLC25A20 gene. This gene gives your body instructions for making “carnitine-acylcarnitine translocase” (CACT). CACT is a transporter that helps in the process of breaking down a certain type of fat, called “long-chain fatty acids.” Long-chain fatty acids are important sources of energy.
When a change causes the SLC25A20 gene to not work, your baby’s body cannot make enough normal copies of CACT. As a result, their body cannot properly break down fats to make energy and get rid of toxins.
CACT deficiency is a genetic condition. Babies inherit it from their biological (birth) parents. To learn more about genetic conditions, visit MedlinePlus Genetics.
- CACT deficiency is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking SLC25A20 gene to their baby. Only babies with two nonworking SLC25A20 genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the SLC25A20 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 SLC25A20 gene, they have a 1 in 4 chance of having a child with CACT deficiency.
- Carriers for CACT 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 CACT deficiency.
- Parents who already have a child with CACT deficiency still have a 1 in 4 chance of having another child with CACT 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 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:
- Regular and frequent meals and snacks
- Diet high in carbohydrates and low in fat
- Medium chain triglyceride (MCT) oil supplements to provide fats the body can break down
- L-carnitine supplements to help the body break down fats (in some cases)
Children who receive early and ongoing treatment for CACT deficiency can help prevent or control symptoms. Even with treatment, some children may still experience heart, liver, or lung problems.