Your browser does not support javascript:   Search for gard hereSearch for news-and-events here.


Genetic and Rare Diseases Information Center (GARD)

Carnitine-acylcarnitine translocase deficiency

See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

My son may have carnitine-acylcarnitine translocase deficiency. Can you provide me with information about this condition?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is carnitine-acylcarnitine translocase deficiency?

Carnitine-acylcarnitine translocase deficiency is a condition that prevents the body from converting certain fats called long-chain fatty acids into energy, particularly during periods without food (fasting). Carnitine, a natural substance acquired mostly through the diet, is used by cells to process fats and produce energy. People with this disorder have a faulty transporter that disrupts carnitine's role in processing long-chain fatty acids.[1] Carnitine-acylcarnitine translocase deficiency is a type of fatty acid oxidation disorder. There are two forms of carnitine-acylcarnitine translocase deficiency. The most common type happens in newborns. A milder, less common type happens in older infants and children.[2]
Last updated: 7/26/2013

How common is carnitine-acylcarnitine translocase deficiency?

Carnitine-acylcarnitine translocase deficiency is very rare; approximately 30 cases have been confirmed.[1]
Last updated: 7/26/2013

What are the signs and symptoms of carnitine-acylcarnitine translocase deficiency?

The signs of carnitine-acylcarnitine translocase deficiency usually begin within the first few hours after birth. Seizures, an irregular heartbeat (arrhythmia), and breathing problems are often the first signs of this disorder. This disorder may also result in an extremely low level of ketones, which are products of fat breakdown that are used for energy. Low blood sugar (hypoglycemia) is another major feature. Together these signs are called hypoketotic hypoglycemia, which can result in unconsciousness and seizures. Other signs that are often present include excess ammonia in the blood (hyperammonemia), an enlarged liver (hepatomegaly), heart abnormalities (cardiomyopathy), and muscle weakness. This disorder can cause sudden infant death.[1]

Children with the mild type of carnitine-acylcarnitine translocase 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.[2]
Last updated: 7/26/2013

What causes carnitine-acylcarnitine translocase deficiency?

Carnitine-acylcarnitine translocase deficiency occurs when an enzyme, called "carnitine-acylcarnitine translocase" (CAT), 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 to break down fat already stored in the body.[2]

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 for energy when we don't eat for a stretch of time - like when we miss a meal or when we sleep.[2]

When the CAT normal enzyme is missing or not working well, 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.[2]

Last updated: 7/26/2013

What genes are associated with carnitine-acylcarnitine translocase deficiency?

Mutations in the SLC25A20 gene cause carnitine-acylcarnitine translocase deficiency.[1] The SLC25A20 gene provides instructions for making a transporter called carnitine-acylcarnitine translocase. Carnitine, a naturally occurring substance obtained mainly from the diet, is necessary for cells to break down fats for energy. The carnitine-acylcarnitine translocase transporter is made in large amounts in the heart, muscles used for movement (skeletal muscles), and the liver. This transporter transfers carnitine linked to fats called long-chain fatty acids into mitochondria, the energy-producing centers within cells. Carnitine-acylcarnitine translocase also transports free carnitine out of the mitochondria.[3]

Mutations in the SLC25A20 gene lead to the production of a defective version of carnitine-acylcarnitine translocase. A shortage of functional transporters prevents long-chain fatty acids from food and fats stored in the body from being broken down and processed. As a result, these fatty acids are not converted into energy, which can lead to characteristic signs and symptoms of this disorder, such as weakness, hypoglycemia, and an irregular heartbeat. Excess long-chain fatty acids, with or without carnitine attached to them, can affect the electrical properties of heart (cardiac) cells. This abnormal accumulation of fatty acids can cause heart damage and an irregular heart beat that can lead to cardiac arrest. Fatty acids may also build up in other tissues and can damage the liver and muscles, resulting in serious, sometimes life-threatening, complications.[1]
Last updated: 7/26/2013

How is carnitine-acylcarnitine inherited?

Carnitine-acylcarnitine translocase deficiency is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.[1]
Last updated: 7/26/2013

Is there genetic testing available for carnitine-acylcarnitine translocase deficiency?

Genetic testing for carnitine-acylcarnitine translocase deficiency can be done on a blood sample. Genetic testing, also called DNA testing, looks for changes in the pair of genes that cause carnitine-acylcarnitine translocase deficiency. 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 carnitine-acylcarnitine translocase deficiency, however, it can be helpful for carrier testing or prenatal diagnosis.[2]
Last updated: 7/26/2013

Can carnitine-acylcarnitine translocase deficiency be identified by any other means?

Carnitine-acylcarnitine translocase deficiency can also be confirmed by a special enzyme test on a skin sample. Talk to your doctor or genetic counselor if you have questions about testing for carnitine-acylcarnitine translocase deficiency.[2]
Last updated: 7/26/2013

How might carnitine-acylcarnitine translocase deficiency be treated?

Although there is no standard treatment plan for carnitine-acylcarnitine translocase deficiency, there are treatments that have been found to be helpful in the management of this condition. Certain treatments may be helpful for some children but not others. When necessary, treatment are usually needed throughout life. Children with carnitine-acylcarnitine translocase deficiency should be followed by a metabolic doctor  and a dietician in addition to their primary doctor.[2]

Aggressive treatment of hypoglycemia, hyperammonemia and prevention of lipolysis (the breakdown of fat stored in fat cells) in the newborn may be lifesaving.[4] Infants and young children with carnitine-acylcarnitine translocase deficiency need to eat frequently to prevent a metabolic crisis. In general, it is often suggested that infants be fed every four to six hours, although some babies need to eat even more frequently than this. It is important that infants be fed during the night. They may need to be woken up to eat if they do not wake up on their own. Sometimes a low-fat, high carbohydrate diet is advised. Carbohydrates give the body many types of sugar that can be used as energy. In fact, for children needing this treatment, most food in the diet should be carbohydrates (bread, pasta, fruit, vegetables, etc.) and protein (lean meat and low-fat dairy food). Some children may be helped by taking L-carnitine. This is a safe and natural substance that helps body cells make energy. It also helps the body get rid of harmful wastes. However, supplementation with carnitine remains controversial, as its efficacy remains unknown.[4] Medium Chain Triglyceride oil (MCT oil) is sometimes used as part of the food plan for people with carnitine-acylcarnitine translocase deficiency. This special oil has medium chain fatty acids that people with carnitine-acylcarnitine translocase deficiency can use in small amounts for energy.[2]

You may be instructed to call your child's doctor at the start of any illness. Children with carnitine-acylcarnitine translocase 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.[2]

Last updated: 7/26/2013

What is the prognosis for children with carnitine-acylcarnitine translocase deficiency?

Prompt and careful treatment may help prevent or control symptoms in children with carnitine-acylcarnitine translocase 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.[2]
Last updated: 7/26/2013

See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.