Lipid Biochemistry USMLE Step 1 Practice Question
A 42-year-old man with familial hypercholesterolemia presents with tendon xanthomas and premature coronary artery disease. Laboratory studies show LDL cholesterol of 520 mg/dL despite atorvastatin therapy. A genetic mutation preventing normal LDL receptor internalization is suspected. Which of the following best explains his inability to respond adequately to statin therapy?
Answer choices
- AIncreased lipoprotein lipase activity in peripheral tissues
- BEnhanced VLDL synthesis overwhelming hepatic lipid metabolism
- CImpaired LDL receptor-mediated endocytosis preventing cholesterol-lowering feedbackCorrect answer
- DDeficiency of apolipoprotein B-100 preventing LDL particle formation
- EIncreased activity of HMG-CoA reductase compensating for statin inhibition
- FPCSK9 gain-of-function accelerating LDL receptor degradation
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