Question

Maple syrup urine disease is a disease of

• A. Metabolism of carbohydrates
• B. Metabolism of amino acids
• C. Metabolism of nucleotides
• D. Metabolism of lipids

Hint:

Associate Maple Syrup Urine Disease (MSUD) with the mnemonic "I Love Vermont maple syrup":
Isoleucine, Leucine, Valine are the three branched-chain amino acids that accumulate.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Inborn errors of metabolism are genetic disorders caused by mutations that disrupt specific metabolic pathways.
Many of these disorders affect the breakdown of amino acids, leading to the accumulation of toxic intermediates.

Step 2: Detailed Explanation:
Maple Syrup Urine Disease (MSUD) is an autosomal recessive metabolic disorder.
It is caused by a deficiency in the branched-chain alpha-keto acid dehydrogenase (BCKAD) complex.
This multi-subunit enzyme complex is responsible for the oxidative decarboxylation of the branched-chain amino acids (BCAAs): leucine, isoleucine, and valine.
When this enzyme complex is inactive, these three amino acids and their toxic alpha-keto acid byproducts accumulate in blood and tissues.
The accumulation of these compounds leads to ketoacidosis, progressive neurodegeneration, and a sweet, maple syrup-like odor in the urine.
This odor is caused by the excretion of alpha-ketoisocaproate (a byproduct of leucine).
Since valine, leucine, and isoleucine are essential amino acids, MSUD is classified as an inborn error of amino acid metabolism.

Step 3: Final Answer:
Maple syrup urine disease is a genetic disorder of amino acid metabolism.