Abstract

Very long-chain acyl-coenzyme A dehydrogenase deficiency (VLCADD) is a fatty-acid metabolism disorder which prevents the body from converting certain fats to energy, particularly during periods without food.

Those affected by this disorder have inadequate levels of an enzyme that breaks down a group of fats called very long-chain fatty acids.

Signs/symptoms

Signs and symptoms can include:

- hypoglycemia

- lethergy

- hepatomegaly

- muscle pain

- cardiomyopathy

Genetics

Mutations in the "ACADVL" gene lead to inadequate levels of an enzyme called very long-chain acyl-coenzyme A (CoA) dehydrogenase. Without this enzyme, very long-chain fatty acids from food and fats stored in the body cannot be degraded 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 lethargy and hypoglycemia. Levels of very long-chain fatty acids or partially degraded fatty acids may build up in tissues and can damage the heart, liver, and muscles, causing more serious complications.

Diagnosis

Typically, initial signs and symptoms of this disorder occur during infancy and include low blood sugar (hypoglycemia), lack of energy (lethargy), and muscle weakness. There is also a high risk of complications such as liver abnormalities and life-threatening heart problems. Symptoms that begin later in childhood, adolescence, or adulthood tend to be milder and usually do not involve heart problems. Episodes of very long-chain acyl-coenzyme A dehydrogenase deficiency can be triggered by periods of fasting, illness, and exercise.

It is common for babies and children with the early and childhood types of VLCADD to have episodes of illness called metabolic crises. Some of the first symptoms of a metabolic crisis are: extreme sleepiness, behavior changes, irritable mood, poor appetite.

Some of these other symptoms of VLCADD in infants may also follow: fever, nausea, diarrhea, vomiting, hypoglycemia.

Treatment

If a metabolic crisis is not treated, a child with VLCADD can develop: breathing problems, seizures, coma, sometimes leading to death.