Abetalipoproteinemia (Bassen-Kornzweig syndrome) results from deficiency of microsomal triglyceride transfer protein (MTP). Which lipoprotein particles are absent in plasma?
- A HDL and LDL only
- B Chylomicrons, VLDL, and LDL (all apoB-containing lipoproteins) ✓
- C IDL and VLDL only
- D All lipoproteins including HDL
Correct answer: B. Chylomicrons, VLDL, and LDL (all apoB-containing lipoproteins)
Explanation
MTP is required for loading apolipoprotein B (apoB-48 in intestine, apoB-100 in liver) with lipids during assembly of chylomicrons and VLDL respectively. Without MTP, apoB cannot be lipidated, and both chylomicrons and VLDL fail to be secreted. Since LDL is derived from VLDL catabolism, LDL is also absent. HDL assembly is independent of MTP and is preserved. Clinically, fat-soluble vitamin deficiency (especially E and A) leads to retinitis pigmentosa and ataxia.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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