Short-chain acyl-coenzyme A dehydrogenase deficiency

Short-chain acyl-coenzyme A (CoA) dehydrogenase deficiency (SCAD) is a rare condition that prevents the body from converting certain fats into energy, especially during periods without food (fasting). People with this disorder are not able to break down a certain group of fats called short-chain fatty acids efficiently. Some affected infants will exhibit vomiting, low blood sugar (hypoglycemia), a lack of energy (lethargy), poor feeding, and failure to gain weight and grow at the expected rate (failure to thrive). Other features of this disorder may include poor muscle tone (hypotonia), seizures, developmental delays, and a small head size (microcephaly). The symptoms of short-chain acyl-CoA dehydrogenase deficiency may be triggered by periods of fasting or during illnesses such as viral infections. In some cases, signs and symptoms may not appear until adulthood, when some individuals may develop muscle weakness and wasting. Other people with gene mutations that can cause this disorder may have such mild symptoms that they are never diagnosed.

This disorder is thought to affect approximately 1 in 40,000 to 100,000 newborns.

Mutations in the ACADS gene cause short-chain acyl-coenzyme A dehydrogenase deficiency.

Mutations in the ACADS gene lead to inadequate levels of an enzyme called short-chain acyl-CoA dehydrogenase. This enzyme is important for the breakdown of short-chain fatty acids. Reduced levels of this enzyme prevent short-chain fatty acids from being further broken down and processed in the mitochondria (the energy-producing centers inside cells). As a result, these short-chain fatty acids are not converted into energy, which can lead to the signs and symptoms of this disorder, such as lethargy and hypoglycemia.

Read more about the ACADS gene.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.