Isobutyryl-CoA dehydrogenase deficiency

Isobutyryl-CoA dehydrogenase (IBD) deficiency is a condition that disrupts the breakdown of certain proteins. Normally, proteins from food are broken down into parts called amino acids. Amino acids can be further processed to provide energy for growth and development. People with IBD deficiency have inadequate levels of an enzyme that helps break down a particular amino acid called valine.

Most people with IBD deficiency are asymptomatic, which means they do not have any signs or symptoms of the condition. A few children with IBD deficiency have developed features such as a weakened and enlarged heart (dilated cardiomyopathy), weak muscle tone (hypotonia), and developmental delay. This condition may also cause low numbers of red blood cells (anemia) and very low blood levels of carnitine, which is a natural substance that helps convert certain foods into energy. The range of signs and symptoms associated with IBD deficiency remains unclear because very few affected individuals have been reported.

IBD deficiency is a rare disorder; approximately 22 cases have been reported in the medical literature.

Mutations in the ACAD8 gene cause IBD deficiency. This gene provides instructions for making the IBD enzyme, which is involved in breaking down valine. ACAD8 gene mutations reduce or eliminate the activity of the IBD enzyme. As a result, valine is not broken down properly. Impaired processing of valine may lead to reduced energy production and the features of IBD deficiency.

Read more about the ACAD8 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.