Lipid Biochemistry USMLE Step 1 Practice Question
A 3-year-old boy presents with failure to thrive, fatty stools, and cholestasis. Laboratory testing reveals severely elevated triglycerides (1200 mg/dL), very low cholesterol (80 mg/dL), and fat-soluble vitamin deficiencies. Genetic testing reveals mutations in the microsomal triglyceride transfer protein (MTP) gene. Which of the following pathophysiologic processes is most directly impaired?
Answer choices
- AConversion of cholesterol to pregnenolone
- BHepatic cholesterol uptake via LDL receptor
- CLipoprotein lipase-mediated hydrolysis of triglycerides
- DIntestinal cholesterol absorption in the terminal ileum
- EApolipoprotein B-100 lipidation and VLDL assemblyCorrect answer
- FChylomicron formation and apolipoprotein B-48 lipidation in the intestine
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.