In hereditary spherocytosis due to ankyrin deficiency, the primary structural consequence is:
- A Loss of spectrin-actin cytoskeleton anchorage to the lipid bilayer, causing membrane vesiculation and loss of surface area ✓
- B Deficiency of band 3 leading to chloride-bicarbonate exchanger dysfunction
- C Absent GPI anchor formation with complement-mediated lysis
- D Deficient 4.2 protein causing increased cation permeability
Explanation
Ankyrin links β-spectrin to band 3 (anion exchanger); its deficiency disconnects the spectrin-actin cytoskeletal lattice from the lipid bilayer. The unsupported lipid bilayer vesiculates over time, progressively reducing RBC surface-to-volume ratio and producing spherocytes. These rigid, non-deformable cells are trapped and destroyed in the splenic sinusoids (extravascular hemolysis). GPI anchor deficiency characterizes PNH. Increased cation permeability with 4.2 deficiency is a lesser mechanism. Band 3 deficiency also causes spherocytosis but the primary mechanism of ankyrin deficiency is skeletal uncoupling.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.