Children and Youth with Special Health Needs (CYSHN)
Carnitine Acylcarnitine Translocase (CACT ) Deficiency
On this page...
- What is CACT deficiency?
- What causes CACT deficiency?
- What causes the CACT enzyme to be absent or not working correctly?
- How is CACT deficiency inherited?
- Is there genetic testing available?
- What other testing is available?
- Can you test during pregnancy?
- Can other members of the family have CACT deficiency or be carriers?
- Can other family members be tested?
- How many people have CACT deficiency?
- Does CACT deficiency happen more often in a certain ethnic group?
- Does CACT deficiency go by any other names?
- What is the treatment for CACT deficiency?
- What happens when CACT deficiency is treated?
- If CACT deficiency is not treated, what problems occur?
This fact sheet contains general information about CACT deficiency. Every child is different and some of this information may not apply to your child specifically. Not all is known about CACT deficiency and, at present, there is no standard treatment plan. Certain treatments may be recommended for some children but not others. Children with CACT deficiency should be followed by a metabolic doctor in addition to their primary doctor.
What is CACT deficiency?
CACT deficiency stands for “carnitine acylcarnitine translocase deficiency”. It is one type of fatty acid oxidation disorder. People with CACT deficiency have problems breaking down fat into energy for the body.
Fatty Acid Oxidation Disorders:
Fatty acid oxidation disorders (FAODs) are a group of rare inherited conditions. They are caused by enzymes that do not work properly.
A number of enzymes are needed to break down fats in the body (a process called fatty acid oxidation). Problems with any of these enzymes can cause a fatty acid oxidation disorder. People with FAODs cannot properly break down fat from either the food they eat or from fat stored in their bodies.
The symptoms and treatment vary between different FAODs. They can also vary from person to person with the same FAOD. See the fact sheets for each specific FAOD.
FAODs are inherited in an autosomal recessive manner and affect both males and females.
What causes CACT deficiency?
CACT deficiency occurs when an enzyme, called “carnitine acylcarnitine translocase” (CACT) is either missing or not working properly. This enzyme's job is to help change certain fats in the food we eat into energy. It also helps break down fat already stored in the body.
Energy from fat keeps us going whenever our bodies run low of their main source of energy, a type of sugar called glucose . Our bodies rely on fat when we don't eat for a stretch of time – like when we miss a meal or when we sleep.
When the CACT enzyme is missing or not working, the body cannot use fat for energy, and must rely solely on glucose. Although glucose is a good source of energy, there is a limited amount available. Once the glucose has been used up, the body tries to use fat without success. This leads to low blood sugar, called hypoglycemia, and to the build up of harmful substances in the blood
Genes tell the body to make various enzymes. People with CACT deficiency have a pair of genes that do not work correctly. Because of the changes in this pair of genes, the CACT enzyme either does not work properly or is not made at all.
How is CACT deficiency inherited?
CACT deficiency is inherited in an autosomal recessive manner. It affects both boys and girls equally.
Everyone has a pair of genes that make the CACT enzyme. In children with CACT deficiency, neither of these genes works correctly. These children inherit one non-working gene for the condition from each parent.
Parents of children with CACT deficiency rarely have the disorder. Instead, each parent has a single non-working gene for CACT deficiency. They are called carriers. Carriers do not have the condition because the other gene of this pair is working correctly.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have CACT deficiency. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.
Genetic counseling is available to families who have children with CACT deficiency. Genetic counselors can answer your questions about how the condition is inherited, choices during future pregnancies, and how to test other family members. Ask your doctor about a referral to a genetic counselor.
Is there genetic testing available?
Genetic testing for CACT deficiency can be done on a blood sample. Genetic testing, also called DNA testing, looks for changes in the pair of genes that cause the condition. In some affected children, both gene changes can be found. However, in other children, neither or only one of the two gene changes can be found, even though we know they are present.
DNA testing is not necessary to diagnose your child. It can be helpful for carrier testing or prenatal diagnosis, discussed below.
What other testing is available?
CACT deficiency can be confirmed by a special enzyme test on a skin sample. Your doctor or genetic counselor can answer your questions about testing for CACT deficiency.
Can you test during pregnancy?
If both gene changes have been found in the child with CACT deficiency, DNA testing can be done during future pregnancies. The sample needed for this test is obtained by either CVS or amniocentesis. CVS stands for Chorionic Villus Sampling, which is a special test done early in pregnancy. During CVS, a small sample of the placenta is removed for genetic testing.
If DNA testing would not be helpful, testing during pregnancy can be done by an enzyme test on cells from the fetus. Again, the sample needed for this test is obtained by either CVS or amniocentesis
Parents may choose to have testing during pregnancy or wait until birth to have the baby tested. A genetic counselor can talk to you about your choices and answer questions about prenatal testing or testing your baby after birth.
Can other members of the family have CACT deficiency or be carriers?
Having CACT deficiency
The brothers and sisters of a baby with CACT deficiency have a chance of being affected even if they haven't had symptoms. Finding out whether other children in the family have this condition is important because early treatment may prevent serious health problems. Talk to your doctor or genetic counselor about testing your other children for CACT deficiency.
CACT deficiency carriers
Brothers and sisters who do not have CACT deficiency still have a chance to be carriers like their parents. Except in special cases, carrier testing should only be done in people over 18 years of age.
Each of the parents' brothers and sisters has a 50% chance to be a carrier. It is important for other family members to be told that they could be carriers. There is a small chance they are also at risk to have children with CACT deficiency.
When both parents are carriers for CACT deficiency, newborn screening results are not sufficient to rule out the condition in a newborn baby. In this case, special diagnostic testing should be done in addition to newborn screening.
During pregnancy, women carrying fetuses with CACT may be at increased risk to develop serious medical problems. Some women carrying fetuses with Fatty Acid Oxidation Disorders have developed:
- excessive vomiting
- abdominal pain
- high blood pressure
- abnormal fat storage in the liver
- severe bleeding
All women with a family history of CACT should share this information with their obstetricians and other health care providers before and during any future pregnancies. Knowing about these risks allows better medical care and early treatment if needed.
Can other family members be tested?
Diagnostic testing for CACT deficiency
Brothers and sisters of an affected child can be tested for CACT deficiency using either DNA testing or a special enzyme test.
Carrier testing for CACT deficiency
If both gene changes have been found in the child with CACT deficiency, other family members can have DNA testing to see if they are carriers.
If DNA testing would not be helpful, other methods of carrier testing may be available. Your metabolic doctor or genetic counselor can answer your questions about carrier testing.
How many people have CACT deficiency?
CACT deficiency is very rare. The actual incidence is unknown.
Does CACT deficiency happen more often in a certain ethnic group?
No, CACT deficiency does not happen more often in any specific race, ethnic group, geographical area or country.
Does CACT deficiency go by any other names?
CACT deficiency is sometimes also called:
- Carnitine acylcarnitine carrier (CAC)
- CAT deficiency
What is the treatment for CACT deficiency?
Your baby's primary doctor may work with a metabolic doctor and a dietician to care for your child.
Certain treatments may be advised for some children but not others. When necessary, treatment is usually needed throughout life. The following are treatments sometimes recommended for children with this condition:
Avoid going a long time without food
Your metabolic doctor will continue to advise you on how often your child should eat as he or she gets older. When they are well, many teens and adults with CACT deficiency can go without food for up to 12 hours without problems. The other treatments usually need to be continued throughout life.
People with CACT deficiency cannot use particular building blocks of fat called "long chain fatty acids". A dietician can help you create a food plan low in these fats. Any diet changes should be made under the guidance of a dietician experienced with CACT deficiency.
Ask your doctor whether your child needs to have any changes in his or her diet.
L-carnitine and MCT oil
Your doctor will decide whether or not your child needs L-carnitine. Unless you are advised otherwise, use only L-carnitine prescribed by your doctor. Do not use L-carnitine without checking with your doctor.
Medium Chain Triglyceride oil (MCT oil) is sometimes used as part of the food plan for people with CACT deficiency. This special oil has medium chain fatty acids that people with CACT deficiency can use in small amounts for energy. Your metabolic doctor or dietician can guide you in how to use this supplement. You will need to get a prescription from your doctor to get MCT oil
Call your doctor at the start of any illness:
Children with CACT deficiency need to eat extra starchy food and drink more fluids during any illness - even if they may not feel hungry - or they could develop a metabolic crisis. Children who are sick often don't want to eat. If they won't or can't eat, children with CACT deficiency may need to be treated in the hospital to prevent a metabolic crisis. Ask your metabolic doctor if you should carry a special travel letter with medical instructions for your child's care.
What happens when CACT deficiency is treated?
Prompt and careful treatment may help prevent or control symptoms in children with CACT deficiency. However, some children continue to have metabolic crises and other health problems despite treatment. Even with treatment, there is a risk of death, especially in newborns with symptoms.
If CACT deficiency is not treated, what problems occur?
CACT deficiency can cause episodes of illness called metabolic crises. Some of the first symptoms of a metabolic crisis are:
- extreme sleepiness
- behavior changes
- irritable mood
- poor appetite
Other symptoms then follow:
If a metabolic crisis is not treated, a child with CACT deficiency can develop:
- muscle weakness
- breathing problems
- coma, sometimes leading to death
There are two forms of CACT deficiency. The most common type happens in newborns. A milder, less common type happens in older infants and children.
CACT deficiency in newborns
Newborns with CACT deficiency often show symptoms within the first week of life. Episodes of metabolic crisis are common. High levels of ammonia in the blood can occur. This can cause serious brain damage.
Newborns with CACT may also have:
- low muscle tone (floppy muscles and joints) and muscle weakness
- enlarged liver
- heart problems and enlarged heart
- breathing problems
Babies who are not treated usually die of heart problems, breathing problems, liver failure or high levels of ammonia in the blood.
CACT deficiency in children
Children with the mild type of CACT deficiency usually start having symptoms before age three. They are at risk to have episodes of metabolic crisis, but usually do not have heart problems.
In both types of CACT deficiency, symptoms often happen after having nothing to eat for more than a few hours. Symptoms are also more likely when a person with CACT deficiency gets sick or has an infection.
Where can I find more information?
National Library of Medicine Genetics Home Reference: Carnitine-Acylcarnitine Translocase Deficiency http://ghr.nlm.nih.gov/condition/carnitine-acylcarnitine-translocase-deficiency
Fatty Oxidation Disorders (FOD) Family Support Group
Organic Acidemia Association
United Mitochondrial Disease Foundation
CLIMB (Children Living with Inherited Metabolic Disorders)
Minnesota Family Support for Fatty Acid Oxidation Disorder (FAOD) - Contact: firstname.lastname@example.org
Medically Prescribed Formula: a table that provides a list of commonly prescribed medical foods and formulas and /or medication for this disorder.
For additional genetics information and resources:
- Genetic Alliance
- Region 4 Genetics Collaborative
- Partnering with your Doctor The Medical Home Approach: A guide for families with children who have genetic conditions - The Guide is intended to be a user-friendly, hands-on tool to support families of children who have genetic conditions to move forward in obtaining and providing a medical home for their children. The guide provides definitions, examples and tools for families to use when working with the doctor to develop a medical home.
More help available from Children and Youth with Special Health Needs (CYSHN):
- Resources: Financial and Other
- Early Childhood Intervention
- Resources for Children and Families
- Youth and Young Adults - Planning for the Future
- Emergency Planning
- Medical Home
We would like to acknowledge the Star G Project. The information on the fact sheet was obtained from the Star G Project. For the most up-to-date information on the disorder please visit their web site at http://www.newbornscreening.info. Each fact sheet was extensively reviewed by family support groups, metabolic specialists across the country and the Star G steering committee.
THIS INFORMATION DOES NOT PROVIDE MEDICAL ADVICE. All content, including text, graphics, images and information are for general informational purposes only. You are encouraged to confer with your doctor or other health care professional with regard to information contained on this information sheet. After reading this information sheet, you are encouraged to review the information carefully with your doctor or other healthcare provider. The Content is not intended to be a substitute for professional medical advice, diagnosis or treatment. NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE, OR DELAY IN SEEKING IT, BECAUSE OF SOMETHING YOU HAVE READ ON THIS INFORMATION SHEET.
|Updated Wednesday, 01-Aug-2012 13:26:14 CDT|