Lipid Biochemistry USMLE Step 1 Practice Question
A 35-year-old man of Mediterranean descent presents with orange discoloration of palms and soles and corneal infiltrates. Vital signs are stable (BP 128/82, HR 72, RR 14). Laboratory findings reveal HDL cholesterol of 5 mg/dL and markedly elevated serum lathosterol despite strict low-fat diet adherence. Lipid electrophoresis shows absent apolipoprotein A-I. He denies alcohol use. Which gene defect is most likely responsible?
Answer choices
- AAPOB (apolipoprotein B)
- BApoA-I (apolipoprotein A-I)
- CSR-B1 (scavenger receptor B1)
- DLCAT (lecithin-cholesterol acyltransferase)Correct answer
- EABCA1 (ATP-binding cassette A1)
- FCETP (cholesteryl ester transfer protein)
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