DBT

The DBT gene provides instructions for making part of an enzyme complex (a group of enzymes that work together) called branched-chain alpha-keto acid dehydrogenase, or BCKD. Specifically, the protein produced from the DBT gene forms a critical part of the enzyme complex called the E2 component.

The BCKD enzyme complex is responsible for one step in the normal breakdown of three protein building blocks (amino acids). These amino acids—leucine, isoleucine, and valine—are obtained from the diet. They are present in many kinds of food, particularly protein-rich foods such as milk, meat, and eggs. The BCKD enzyme complex is active in mitochondria, which are specialized structures inside cells that serve as energy-producing centers. The breakdown of leucine, isoleucine, and valine produces molecules that can be used for energy.

maple syrup urine disease - caused by mutations in the DBT gene

More than 30 mutations in the DBT gene have been identified in people with maple syrup urine disease, most often in individuals with mild variants of the disorder. Mutations in the DBT gene include changes in single DNA building blocks (base pairs) and insertions or deletions of a small amount of DNA in the DBT gene.

Mutations in the DBT gene disrupt the normal function of the E2 component, preventing the BCKD enzyme complex from effectively breaking down leucine, isoleucine, and valine. As a result, these amino acids and their byproducts build up in the body. This accumulation is toxic to cells and tissues, particularly in the nervous system. The buildup of these substances can lead to seizures, developmental delay, and the other medical problems associated with maple syrup urine disease.