BCKDHB

An enzyme involved in the metabolism of branched-chain amino acids

BCKDHB (Branched-chain alpha-keto acid dehydrogenase E1 component subunit beta) is a gene that encodes a protein involved in the catabolism of branched-chain amino acids (BCAAs), which include leucine, isoleucine, and valine. This protein is a component of the branched-chain alpha-keto acid dehydrogenase complex (BCKD complex), which is crucial for the breakdown of these amino acids.

Function

The BCKD complex is a multi-enzyme complex located in the mitochondria and is responsible for the oxidative decarboxylation of branched-chain alpha-keto acids derived from BCAAs. The BCKDHB gene encodes the beta subunit of the E1 component of this complex. The E1 component is a heterotetramer composed of two alpha and two beta subunits, encoded by the BCKDHA and BCKDHB genes, respectively.

Clinical significance

Mutations in the BCKDHB gene can lead to a metabolic disorder known as Maple syrup urine disease (MSUD). This condition is characterized by the accumulation of branched-chain amino acids and their corresponding keto acids in the body, leading to neurological damage and other serious health issues if untreated. MSUD is named for the distinctive sweet odor of the urine in affected individuals, reminiscent of maple syrup.

Genetics

The BCKDHB gene is located on chromosome 6 at the q14.1 position. It is inherited in an autosomal recessive manner, meaning that two copies of the mutated gene, one from each parent, are necessary for the manifestation of the disease.

Research and developments

Research into BCKDHB and the BCKD complex is ongoing, with studies focusing on understanding the precise mechanisms of enzyme function, the impact of specific mutations, and potential therapeutic approaches for MSUD. Gene therapy and enzyme replacement therapy are areas of active investigation.

Also see

• Branched-chain amino acids
• Maple syrup urine disease
• BCKDHA
• Metabolic disorders