Lipid Biochemistry USMLE Step 1 Practice Question
A 45-year-old man presents with premature coronary artery disease and xanthomas on his Achilles tendons. Laboratory studies show LDL cholesterol of 520 mg/dL despite a low-fat diet. His father died of myocardial infarction at age 52. Genetic testing confirms a mutation in the LDL receptor gene. Which of the following mechanisms best explains his lipid abnormality?
Answer choices
- AIncreased conversion of VLDL to IDL due to hepatic lipase deficiency
- BOverproduction of cholesterol by the liver independent of feedback inhibition
- CIncreased lipoprotein lipase activity in peripheral tissues
- DDecreased hepatic uptake of LDL due to nonfunctional LDL receptorsCorrect answer
- EImpaired apolipoprotein B synthesis leading to VLDL accumulation
- FLysosomal acid lipase deficiency (cholesterol ester storage disease)
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