Very-Long-Chain Acyl-CoA dehydrogenase (VLCAD) deficiency is a disorder in which the body doesn’t make enough of an enzyme called very-long-chain acyl-coenzyme A dehydrogenase, which is essential for turning a type of fat into energy.
Without enough of this enzyme, the body can’t convert fats into energy properly. This leads to low blood sugar (hypoglycemia) and feelings of weakness or tiredness. There are three types of this disorder, and they vary in how severe they are.
Early-Onset Form: In the most severe type, symptoms appear in the first few months of life. This can lead to heart problems that can be life-threatening. Babies may have poor muscle tone, low blood sugar, lack of energy, and an enlarged liver. This type of VLCAD deficiency can lead to early death.
Childhood-Onset Form: This type shows up in early childhood but usually doesn’t affect the heart. People with this form may have an enlarged liver, episodes of low blood sugar, liver problems, and sometimes muscle weakness.
Late-Onset Form: The mildest form shows mild symptoms starting in adolescence or adulthood. Some may not have any symptoms until times of fasting, illness, or exercise. This form usually doesn’t cause heart problems or low blood sugar. People may experience occasional muscle cramps and breakdown, which can lead to kidney damage. Symptoms often worsen after strenuous exercise or stress.
Treatment involves special diets. For severe cases, it may include intravenous glucose or a low-fat formula. Detecting the condition early and proper treatment can prevent heart issues. People with VLCAD deficiency should avoid high-fat foods and long periods without eating. It’s important to get extra medical care during illness, and adults experiencing muscle breakdown should stay hydrated and try to lower urine acidity to protect the kidneys.
VLCAD is caused by pathogenic (disease-causing) variants in the ACADVL gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
VLCAD carriers do not typically show symptoms of the disease. However, there may be an increased risk of serious pregnancy complications, particularly in the third trimester, in women carrying a fetus affected with VLCAD.
Other names for this condition are acyl-CoA dehydrogenase very long chain deficiency and very long-chain acyl coenzyme A dehydrogenase deficiency
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Revised November 2023
