Medium Chain Acyl-CoA Dehydrogenase Deficiency

Medium chain acyl CoA dehydrogenase (MCAD) deficiency is an inherited metabolic disorder that stops the body from converting certain fats to energy due to an ineffective enzyme, MCAD. Typically, children affected by MCAD deficiency have symptoms like vomiting, tiredness, and low blood sugar, usually triggered by illness. These symptoms can progress to seizures, breathing difficulties, liver disease, brain damage, coma, and death. Although this disorder usually appears in infancy or childhood, adult onset has been documented. Once the diagnosis is made, life expectancy for individuals affected with MCAD deficiency is excellent. Regular and frequent feeding as well as avoidance of fasting prevents symptoms from recurring. MCAD deficiency is caused by pathogenic variants in the ACADM gene.

MCAD 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.

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

MCAD deficiency affects all ethnicities but it is more common in Europeans and individuals of European descent. In the general population, MCAD deficiency occurs in about 1 in 4,900 to 1 in 17,000 newborns.

Genetics Home Reference: Medium chain acyl CoA dehydrogenase deficiency (MCAD) (http://ghr.nlm.nih.gov/)
The National Organization for Rare Disorders (NORD): (https://www.rarediseases.org)

OMIM [Medium chain acyl CoA dehydrogenase deficiency (MCAD): 201450] (http://www.ncbi.nlm.nih.gov/omim)
Gene Reviews: Medium-chain Acyl-Coenzyme A dehydrogenase deficiency (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Full gene sequencing