Which disorder is characterized by the inability to break down the amino acids leucine, isoleucine, and valine?

The disorder characterized by the inability to break down the amino acids leucine, isoleucine, and valine is Maple syrup urine disease. This metabolic condition is a result of a deficiency in the branched-chain alpha-keto acid dehydrogenase complex, which is critical for processing these specific amino acids. When individuals with this condition consume proteins containing these amino acids, they cannot metabolize them properly, leading to a buildup of toxic substances in the body, which can result in neurological damage if not managed appropriately.

The distinct characteristic of maple syrup urine disease is that urine may have a sweet, maple syrup-like odor due to the accumulation of the amino acids and their byproducts. Without early screening and dietary management, symptoms can become severe, typically presenting in the neonatal period or early childhood.

Other conditions mentioned do not involve amino acid metabolism in the same way. For instance, congenital hypothyroidism involves an underactive thyroid gland, leading to issues with metabolism and growth, but does not directly relate to the metabolism of these branched-chain amino acids. Galactosemia is a disorder affecting the metabolism of galactose, a sugar found in milk and dairy products, while phenylketonuria is a metabolic disorder concerning the amino acid phen