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MBBS QUESTION #10327
Question 1
In the liver, bilirubin is conjugated with glucuronic acid — a step essential for its water solubility and biliary excretion — by which enzyme, which is deficient (to varying degrees) in Gilbert and Crigler-Najjar syndromes?
  • UDP-glucuronyl transferase (UGT1A1)✔️
  • Biliverdin reductase
  • Heme oxygenase
  • Bilirubin oxidase
Correct Answer Explanation
UDP-glucuronyl transferase conjugates bilirubin with glucuronic acid, converting it to the water-soluble form that can be excreted in bile; partial deficiency causes the mild, usually benign unconjugated hyperbilirubinemia of Gilbert syndrome, while near-complete or complete deficiency causes the more severe Crigler-Najjar syndrome.