8. In a Autosomal dominant HS patient the rbc membrane protein electrophoresis will most commonly show deficiency of ?
/1. Spectrin
/2. Ankyrin
/3. Both Ankyrin and Spectrin
/4. Band 3 protein
Answer: MC genetic defect in AD HS is Ankyrin.
Ankyrin-1 plays a pivotal role in the stabilisation of the membrane, providing the main membrane binding site for the spectrin-based membrane skeleton. Since it links β spectrin to band 3, ankyrin deficiency leads to a proportional reduction in spectrin assembly on the membrane despite normal spectrin synthesis.
So the biochemical phenotype (ie rbc protein electrophoresis) of combined spectrin and ankyrin deficiency is the most common abnormality noted in about 40–65% of patients with hereditary spherocytosis.
Note the “catch in Q” genetic defect or biochemical defect is being asked.