Lipid Biochemistry USMLE Step 1 Practice Question
A 55-year-old man develops acute coronary syndrome. His lipid panel shows total cholesterol of 220 mg/dL and LDL of 140 mg/dL, both moderate elevations. However, his Lp(a) level is markedly elevated at 120 nmol/L (normal <50). Genetic analysis shows a polymorphism in the LPA gene affecting lipoprotein(a) production. Which of the following best explains his cardiovascular risk despite moderate LDL levels?
Answer choices
- ALp(a) carries apoB-100 and LDL-C, increasing atherosclerotic burden independently of LDLCorrect answer
- BLp(a) directly activates lipoprotein lipase in coronary arteries
- CLp(a) deficiency is associated with premature myocardial infarction
- DLp(a) competes with HDL for hepatic uptake receptors
- ELp(a) inhibits hepatic LDL receptor expression
- FLp(a) increases triglyceride hydrolysis by hepatic lipase, reducing HDL-C levels
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