Very Long-Chain Acyl-CoA Dehydrogenase Deficiency


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

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is an inherited disorder that is caused by having inadequate amount of the enzyme VLCAD needed to break down certain fats into energy. The symptoms of VLCAD deficiency usually start after a long period of time without eating or during illness. VLCAD deficiency includes three different forms. Infants with early-onset form, the most severe and common form of VLCAD deficiency, show heart enlargement, liver enlargement, low blood sugar, and low muscle tone in the first months of life. This form is fatal if not treated. Some individuals show symptoms starting in early childhood that include liver enlargement and low blood sugar, but no heart problems. Individuals with the late-onset form, the mildest form, develop muscle disease during adulthood. With early detection of this condition, proper management by a special diet, and avoidance of fasting, individuals with VLCAD deficiency usually have normal physical and mental development. pathogenic variants in the ACADVL gene cause VLCAD deficiency.

How is VLCAD deficiency inherited?

VLCAD deficiency is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for VLCAD deficiency. However, the risk to have a child affected with VLCAD deficiency is increased. Testing of reproductive partners is recommended for carriers of VLCAD deficiency.

How common is VLCAD deficiency?

It is suspected that about 1 in 30,000 individuals are affected with the VLCAD deficiency in the USA.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems




Carrier Rates
Detection Rate
Carrier Frequency
General Population > 93% 1 in 86

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