Medicine The genetic variation in drug metabolism pathway that results in severe toxicity of fluorouracil is: A CYP2C9 B Dihydropyrimidine dehydrogenase C Thiopurine-S methyltransferase D CYP2D6 💡 Explanation The genetic variation in drug metabolism pathway that results in severe toxicity of fluorouracil is: ✓ Correct Answer: B. Dihydropyrimidine dehydrogenase