Which enzyme's deficiency leads to maple syrup urine disease, characterized by a distinctive sweet odor of urine?

A Phenylalanine hydroxylase
B Branched-chain alpha-keto acid dehydrogenase complex ✓
C Tyrosinase
D Galactose-1-phosphate uridyltransferase

Explanation

Maple syrup urine disease is caused by a deficiency in the branched-chain alpha-keto acid dehydrogenase complex, resulting in the accumulation of branched-chain amino acids and their corresponding alpha-keto acids, which give urine a characteristic sweet odor.

Source

_OMIM - Maple Syrup Urine Disease
Enzymes in Disease Biochemistry Amino Acid Metabolism Disorders Hard MEDICAL Confidence: high