Lipid Biochemistry USMLE Step 1 Practice Question
A 52-year-old woman presents with xanthomas on her eyelids and Achilles tendons, along with premature coronary artery disease. Laboratory studies show LDL cholesterol of 420 mg/dL despite atorvastatin 80 mg daily, HDL of 35 mg/dL, and normal triglycerides. Her father and paternal grandfather both had myocardial infarctions in their 40s. Which of the following is the most likely genetic defect?
Answer choices
- ALoss-of-function mutation in apolipoprotein B-100
- BGain-of-function mutation in PCSK9
- CLoss-of-function mutation in the LDL receptor geneCorrect answer
- DLoss-of-function mutation in lipoprotein lipase
- EGain-of-function mutation in HMG-CoA reductase
- FLoss-of-function mutation in apolipoprotein E
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