Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a condition that prevents the body from converting certain fats to energy, particularly during periods without food (fasting).
Signs and symptoms of VLCAD deficiency typically appear during infancy or early childhood and can include low blood sugar (hypoglycemia), lack of energy (lethargy), and muscle weakness. Affected individuals are also at risk for serious complications such as liver abnormalities and life-threatening heart problems. When symptoms begin in adolescence or adulthood, they usually involve muscle pain and the breakdown of muscle tissue (rhabdomyolysis). The destruction of muscle tissue releases a protein called myoglobin, which is processed by the kidneys and released in the urine (myoglobinuria). Myoglobin causes the urine to be red or brown.
In both children and adults, problems related to VLCAD deficiency can be triggered by periods of fasting, illness, and exercise. In affected children, this disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.
VLCAD deficiency is estimated to affect 1 in 40,000 to 120,000 people.
Variants (also known as mutations) in the ACADVL gene cause VLCAD deficiency. This gene provides instructions for making an enzyme called very long-chain acyl-CoA dehydrogenase, which is required to break down (metabolize) a group of fats called very long-chain fatty acids. These fatty acids are found in foods and the body's fat tissues. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, fatty acids are also an important energy source for the liver and other tissues.
Variants in the ACADVL gene lead to a shortage (deficiency) of the VLCAD enzyme within cells. Without sufficient amounts of this enzyme, very long-chain fatty acids are not broken down properly. As a result, these fats are not converted to energy, which can lead to the characteristic signs and symptoms of this disorder such as lethargy and hypoglycemia. Very long-chain fatty acids or partially metabolized fatty acids may also build up in tissues and damage the heart, liver, and muscles. This abnormal buildup causes the other signs and symptoms of VLCAD deficiency.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have variants. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they typically do not show signs and symptoms of the condition.
Other Names for This Condition
- Acyl-CoA dehydrogenase very long chain deficiency
- Very long-chain acyl coenzyme A dehydrogenase deficiency
- Very long-chain acyl-coenzyme A dehydrogenase deficiency
- VLCAD deficiency
Additional Information & Resources
Genetic Testing Information
Genetic and Rare Diseases Information Center
Research Studies from ClinicalTrials.gov
Catalog of Genes and Diseases from OMIM
Scientific Articles on PubMed
- Diekman EF, Ferdinandusse S, van der Pol L, Waterham HR, Ruiter JP, Ijlst L, Wanders RJ, Houten SM, Wijburg FA, Blank AC, Asselbergs FW, Houtkooper RH, Visser G. Fatty acid oxidation flux predicts the clinical severity of VLCAD deficiency. Genet Med. 2015 Dec;17(12):989-94. doi: 10.1038/gim.2015.22. Epub 2015 Apr 2. Citation on PubMed
- Evans M, Andresen BS, Nation J, Boneh A. VLCAD deficiency: Follow-up and outcome of patients diagnosed through newborn screening in Victoria. Mol Genet Metab. 2016 Aug;118(4):282-7. doi: 10.1016/j.ymgme.2016.05.012. Epub 2016 May 16. Citation on PubMed
- Laforêt P, Acquaviva-Bourdain C, Rigal O, Brivet M, Penisson-Besnier I, Chabrol B, Chaigne D, Boespflug-Tanguy O, Laroche C, Bedat-Millet AL, Behin A, Delevaux I, Lombès A, Andresen BS, Eymard B, Vianey-Saban C. Diagnostic assessment and long-term follow-up of 13 patients with Very Long-Chain Acyl-Coenzyme A dehydrogenase (VLCAD) deficiency. Neuromuscul Disord. 2009 May;19(5):324-9. doi: 10.1016/j.nmd.2009.02.007. Epub 2009 Mar 26. Citation on PubMed
- Miller MJ, Burrage LC, Gibson JB, Strenk ME, Lose EJ, Bick DP, Elsea SH, Sutton VR, Sun Q, Graham BH, Craigen WJ, Zhang VW, Wong LJ. Recurrent ACADVL molecular findings in individuals with a positive newborn screen for very long chain acyl-coA dehydrogenase (VLCAD) deficiency in the United States. Mol Genet Metab. 2015 Nov;116(3):139-45. doi: 10.1016/j.ymgme.2015.08.011. Epub 2015 Sep 2. Citation on PubMed or Free article on PubMed Central
- Pena LD, van Calcar SC, Hansen J, Edick MJ, Walsh Vockley C, Leslie N, Cameron C, Mohsen AW, Berry SA, Arnold GL, Vockley J; IBEMC. Outcomes and genotype-phenotype correlations in 52 individuals with VLCAD deficiency diagnosed by NBS and enrolled in the IBEM-IS database. Mol Genet Metab. 2016 Aug;118(4):272-81. doi: 10.1016/j.ymgme.2016.05.007. Epub 2016 May 13. Citation on PubMed or Free article on PubMed Central
- Spiekerkoetter U, Sun B, Zytkovicz T, Wanders R, Strauss AW, Wendel U. MS/MS-based newborn and family screening detects asymptomatic patients with very-long-chain acyl-CoA dehydrogenase deficiency. J Pediatr. 2003 Sep;143(3):335-42. Citation on PubMed