Carnitine-Acylcarnitine Translocase Deficiency

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Carnitine-Acylcarnitine Translocase Deficiency (CACT) deficiency is a metabolic disorder caused by a gene defect you inherit from your parents. A fully working Carnitine-Acylcarnitine Translocase helps your body to transport fat (long chain fatty acids) inside your body’s cells and assists in breaking them down so they can be used for energy. With CACT deficiency, you are unable to transport these fats into your body’s cells to be broken down to be used for energy, which causes some of the problems linked with CATC deficiency. The rest of the problems is caused by the cellular build-up of fatty acids that could not be broken down.

There are two subgroups that exist for this condition:

• The more common severe type that occurs in new-borns
• The less common less severe type that occurs in infants and older children

The severe type of CACT deficiency can present symptoms straight from birth. New-borns tend not to make it past 1 month old.

The less severe type of CACT deficiency tends to present symptoms in infancy or childhood. This condition can be managed with assistance from health care professionals, you can live a normal life with this metabolic condition.

We do not know how many people have this disorder. It is very rare with only a small amount of cases that are known. It is also unknown whether it is more common between males and females, but there has been higher incidence in East Asian populations. According to a newborn screening data, it is estimated that the incidence in Australia, Germany, and the United States ranges approximately from 1:750,000 to 1:2,000,000 and in Hong Kong and Taiwan is 1:60,000 and 1:400,000 respectively.

Symptoms of CACT deficiency usually present within the first few hours of birth. Some of the signs and symptoms for you to look out for are:

• Poor feeding
• Excessive sleeping and tiredness
• Muscle weakness or muscle abnormalities
• Breakdown of skeletal muscle
• Brain disease, damage, or malfunction (Encephalopathy)
• Global developmental delay
• Respiratory impairment
• Enlarged Liver may lead to a liver failure
• Heart disease
• Seizures
• Low temperature
• Excessive ammonia within the blood
• Low blood sugar and a low level of ketones (hypoketotic hypoglycemia)
• Excess ammonia in the blood (hyperammonemia)
• Nervous system damage
• Coma

CACT deficiency can be diagnosed by blood test. Your health care professional uses your blood results to measure the levels of acylcarnitine with your blood to check for a deficiency. CACT deficiency can also be diagnosed by molecular testing techniques performed by your health care professional.

Diagnosis of CACT deficiency can sometimes be misinterpreted as carnitine palmitoyl transferase II deficiency. These conditions need to be fully excluded before a diagnosis can be made, the difference between the two conditions is that CACT deficiency tends not to show congenital problems, whereas carnitine palmitoyl transferase II deficiency does.

New-born screening tests for this condition are available in some countries such as Austria, Czech Republic, Germany, Hungary, Iceland, Portugal and Spain.

Currently, there is no treatment for CACT Deficiency. Therefore, treatment is focused on managing individual symptoms and providing comfort and relief in the form of supporting the individual and any family members. A multi-disciplinary team of specialists and support networks will be involved in the management of the condition and to offer practical and emotional support.

This condition is managed by avoiding prolonged periods of fasting and high carbohydrate and low-fat diets. Your dietitian may prescribe you with low doses of long chain fatty acid and medium chain fatty acid supplementation. Your dietitian may prescribe you an Intravenous dose of glucose to be used overnight, this is to ensure your blood sugar levels do not drop to dangerous levels. The use of a dietitian with this condition is important, they will be able to educate you on what food regimes and explain to you any questions you may have regarding your metabolic disorder.

Supportive treatment may include anaplerotic agent triheptanoin, medium-chain triglyceride (MCT) oil or Carnitine supplementation.

Based on the development of specific symptoms, an aggressive rehabilitation therapy, including physical and occupational therapy may be of benefit. Placement of feeding tube and/or feeding therapy may be needed.

CACT Deficiency can only be passed on to a child if both parents have a copy of the faulty gene. This is called autosomal recessive inheritance. A person who has a copy of the faulty gene is known as a carrier.

If both parents are carriers, their child has a one in four (25%) chance of inheriting the disorder, and a one in two chance (50%) of being a carrier. This is the same for each child the parents have.

If the child only inherits one copy of the faulty gene, they will be a carrier but will not have the disorder. In some rare cases, carriers have had mild symptoms of the disorder for which they carry the faulty gene.

Once you are diagnosed, you can speak to a genetic counsellor. They can explain how you may have inherited CACT Deficiency. They can also tell you about genetic testing for the rest of your family. They can provide advice and support if you go on to have children of your own.

If you have previously had a child with CACT Deficiency and go on to have further children, their New-born Screening test should be carried out within 24-48 hours of birth.

References are available on request. Please contact us by phoning 0845 241 2173 or emailing contact@metabolicsupportuk.org [Resource Library No: CFKB10].