Lipid Biochemistry USMLE Step 1 Practice Question
A 7-year-old boy presents with growth retardation, chronic diarrhea, and steatorrhea. Vital signs show weight 15th percentile for age. Laboratory studies reveal fat-soluble vitamin deficiencies (vitamins A, D, E, K), with serum cholesterol of 85 mg/dL. Peripheral blood smear demonstrates acanthocytes. Abdominal imaging shows no biliary obstruction. DNA sequencing identifies mutations in the APOB gene causing premature termination codons. Which lipoprotein cannot be adequately secreted from hepatocytes in this patient?
Answer choices
- ALDL particles only due to defective LDL receptor ligand binding
- BChylomicrons and VLDL due to defective apolipoprotein B-48
- CHDL particles due to impaired apolipoprotein A-I synthesis
- DVLDL and LDL due to defective apolipoprotein B-100Correct answer
- EAll lipoproteins equally due to generalized lipid trafficking defect
- FChylomicrons only due to defective apolipoprotein B-48 synthesis in the intestine
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