Which of the following is a phase II drug metabolism reaction associated with a genetic polymorphism
**Core Concept**
The question is testing the student's knowledge of phase II drug metabolism reactions, specifically those associated with genetic polymorphisms. Phase II reactions involve conjugation of a lipophilic compound with a hydrophilic moiety, making the compound more water-soluble and easier to excrete.
**Why the Correct Answer is Right**
One of the key phase II reactions is glucuronidation, which is mediated by the enzyme UDP-glucuronosyltransferase (UGT). This enzyme is responsible for the majority of glucuronidation reactions in humans. However, UGT is also associated with genetic polymorphisms, which can affect the metabolism of various drugs. For example, the UGT1A1*28 allele is associated with a reduction in UGT1A1 activity, leading to decreased glucuronidation of bilirubin and increased risk of unconjugated hyperbilirubinemia.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a phase II drug metabolism reaction. Phase I reactions typically involve oxidation, reduction, or hydrolysis of a compound, whereas phase II reactions involve conjugation.
* **Option B:** This option is incorrect because it is not associated with a genetic polymorphism. While acetylation is an important phase II reaction, it is not typically associated with genetic variations in the enzyme responsible for the reaction.
* **Option C:** This option is incorrect because it is not a phase II drug metabolism reaction. Methylation is a phase I reaction that involves the addition of a methyl group to a compound.
**Clinical Pearl / High-Yield Fact**
The UGT1A1*28 allele is a classic example of a genetic polymorphism affecting drug metabolism. This allele is associated with increased risk of unconjugated hyperbilirubinemia and is also implicated in the metabolism of various drugs, including irinotecan and SN-38.
**Correct Answer:** C.