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DBT gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

DBT gene

The DBT gene encodes a component of an enzyme complex necessary for breaking down specific amino acids, with mutations leading to maple syrup urine disease.

Normal Function

The DBT gene provides instructions for making part of a group of enzymes called the branched-chain alpha-keto acid dehydrogenase (BCKD) enzyme complex. Specifically, the protein produced from this gene forms a critical piece of the 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): leucine, isoleucine, and valine. These amino acids are obtained from the diet, particularly from protein-rich foods such as milk, meat, and eggs. The BCKD enzyme complex is active in mitochondria, and the breakdown of these amino acids produces molecules that can be used for energy.

Health Conditions Related to Genetic Changes

Maple syrup urine disease

More than 70 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. These variant forms become apparent later in infancy or childhood and can lead to delayed development and other health problems if not treated.

Mutations in the DBT gene include changes in single DNA building blocks (base pairs) and insertions or deletions of DNA. These changes 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, leading to the developmental delays and health problems associated with the disease.

Other Names for This Gene

  • BCATE2
  • dihydrolipoamide branched chain transacylase (E2 component of branched chain keto acid dehydrogenase complex; maple syrup urine disease)
  • E2 component of branched chain keto acid dehydrogenase complex
  • MSUD2
  • ODB2_HUMAN

Frequently Asked Questions

Mutations in the DBT gene, which encodes the E2 component of the BCKD complex, are most frequently associated with the milder, late-onset variants of maple syrup urine disease. Unlike the classic form, which presents with severe symptoms shortly after birth, DBT-related variants often become apparent later in infancy or childhood. This delayed onset allows for a different clinical trajectory where developmental delays may be the primary early sign rather than acute metabolic crisis, though the underlying mechanism of toxic amino acid accumulation remains the same.
Individuals with DBT mutations must strictly limit the intake of the branched-chain amino acids leucine, isoleucine, and valine, which are found in protein-rich foods like meat, milk, and eggs. Because the E2 component is defective, the body cannot break down these specific amino acids, leading to toxic buildup. Management typically involves a specialized diet high in other amino acids and carbohydrates for energy, often supplemented with medical formula, to prevent the neurological damage associated with elevated leucine levels.
Maple syrup urine disease caused by DBT mutations is inherited in an autosomal recessive pattern. This means a person must inherit two copies of the mutated gene, one from each parent, to develop the condition. Parents who are carriers typically do not show symptoms. If both parents are carriers, there is a 25% chance with each pregnancy that the child will have the disorder, a 50% chance the child will be a carrier, and a 25% chance the child will not be affected. Genetic counseling and carrier testing are recommended for family planning.
Yes, with consistent dietary management and medical monitoring, individuals with mild DBT-related variants can often achieve near-normal developmental milestones and lead active lives. The key is preventing the accumulation of toxic amino acids through strict adherence to a low-BCAA diet. Regular monitoring of blood amino acid levels is essential to adjust dietary protein intake as the child grows, ensuring that energy needs are met without triggering metabolic decompensation.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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