Very-Long-Chain acyl-CoA Dehydrogenase Deficiency (VLCAD)

What is very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD)?

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is a fatty acid oxidation disorder that keeps the body from converting certain fats into energy. Fatty acids are the building blocks of the fat in our bodies and the food we eat. They are built like chains, with carbon as the links, and come in difference lengths. A very-long-chain fatty acid is a fatty acid with 22 or more carbons. They are found in food and the body’s fat tissues, and are a major source of energy. Fatty acid oxidation disorders are a group of metabolic deficiencies in which the body cannot breakdown fatty acids in order to produce energy. Many enzymes are needed to break down fats in the body, and problems with these enzymes can cause a fatty oxidation disorder. To learn more about fatty acid oxidation disorders (FODs), click here. Symptoms of VLCAD usually appear during infancy and early childhood but can sometimes start in adulthood. It is estimated to affect one in 40,000 infants, and affects both males and females equally.

What are the symptoms of VLCAD?

Symptoms are often triggered by periods of fasting, exercise, and illness. It is unlikely that each individual will exhibit every single one of these symptoms. They include:

Low blood sugar
Lack of energy
Oversleeping
Irritability
Muscle weakness
Poor appetite
Fever
Vomiting
Diarrhea
Enlarged liver
Heart problems like thickening of the heart muscles (hypertrophic cardiomyopathy)
Muscle pain
Breakdown of muscle tissue

If untreated, VLCAD can cause brain damage and even lead to death. However, if the condition is detected early in life and treated, individuals with VLCAD can often lead healthy lives.

What causes VLCAD?

Human traits are inherited from one’s father and mother. They each contribute a gene, which interacts with the other. VLCAD is inherited in an autosomal recessive pattern, which means that both parents need to pass down a copy of the defective gene for the condition to occur. VLCAD is caused by a mutation in the ACADVL gene, a gene that gives instructions for making an enzyme called very long-chain acyl-CoA dehydrogenase. The body needs that enzyme so it can break down very-long-chain fatty acids. However, when this mutation occurs, it leads to a shortage of the enzyme. As a result, very long-chain fatty acids aren’t converted into energy, which leads to the symptoms discussed above.

How is VLCAD diagnosed?

VLCAD is diagnosed using the following procedures:

Newborn screening
Thorough physical evaluation
Various specialized tests that analyze samples of urine, blood, muscle, skin, liver tissue, and/or white blood cells
Recording of family history

What are the treatments for VLCAD?

VLCAD treatment includes:

Avoiding fasting for more than 10 to 12 hours
Eating often
Having a low-fat, high-carbohydrate diet (in order to avoid eating fats that the body can’t break down)
Nutritional supplements like Medium-chain Triglyceride (MCT) oil
L-carnitine supplements
Genetic counseling