Abetalipoproteinaemia (Bassen-Kornzweig syndrome) is caused by a defect in MTP (microsomal triglyceride transfer protein). The consequence is inability to assemble:

• A LDL particles, causing severely low LDL-C and premature cardiovascular disease
• B HDL particles, causing Tangier disease with low HDL and corneal infiltrates
• C IDL particles only, with normal chylomicrons and VLDL
• D Chylomicrons (in intestine) and VLDL (in liver), causing fat malabsorption and progressive ataxia ✓

Explanation

MTP is essential for loading triglycerides onto apoB-containing lipoproteins (ApoB-48 in intestinal chylomicrons, ApoB-100 in hepatic VLDL). Without MTP, neither chylomicrons nor VLDL can be assembled, causing severe fat malabsorption, failure to absorb fat-soluble vitamins (A, D, E, K), acanthocytosis (thorny RBCs due to altered membrane lipid composition), and progressive spinocerebellar degeneration from vitamin E deficiency. MTP inhibitors (e.g., lomitapide) are used therapeutically in homozygous familial hypercholesterolaemia.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.