Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency

What happens in this disease?

The VLCAD enzyme breaks down very long-chain fatty acids. When this enzyme is missing, these fats cannot be turned into energy. Fat waste products that build up can damage the heart, liver and muscles. There are three types, which begin in infancy, in childhood or later.

Which symptoms can occur?

Symptoms vary depending on the type of the disease. Fasting, illness, exercise, heat or cold can trigger episodes.

• Heart muscle disease and rhythm problems in infancy (in the early type)
• Floppy muscles and weakness
• Low blood sugar
• Enlarged liver (in the childhood type)
• Muscle pain and cramps brought on by exercise (in the late type)
• Muscle breakdown and red or brown urine (in the late type)

How is it diagnosed?

The blood is checked for fat waste products called acylcarnitines, and a typical pattern is seen. The diagnosis is confirmed with a genetic test. If needed, a special enzyme test is done on skin or blood cells.

Treatment and care

The basis of treatment is diet. A meal plan low in long-chain fat and containing special fats is followed. Fasting is avoided, and babies are fed often. Avoiding heavy exercise helps prevent muscle breakdown. In the USA, there is an approved special fat treatment for this group of diseases. The heart and blood values are checked regularly. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through recessive inheritance. The mother and father are usually carriers who show no symptoms. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Recessive diseases can be more common when relatives marry each other. Testing brothers and sisters as well is recommended. Genetic counselling is recommended.