True about Sickle cell anaemia except ?

Ans. is d i.e., Deletion of gene Sickle cell anemia is due to point mutation (not deletion) that leads to substitution of valine for glutamic acid at sixth position of [3-globin chain. SCA occurs more commonly in black people from pas of Sub-Saharan Africa-------------------- Internet. Effect of HbS on RBCs o In deoxygenated condition, the HbS molecules undergo polymerization and aggregation. o With continued deoxygenation, aggregated HbS molecules assemble into long needle-like fibers within red cells, producing a distoed sickle or holly-leaf shape. Sickling of red cells is reversible initialy, i.e., with oxygenation, HbS depolymerizes and cell shape normalizes. o However, with repeated episodes of deoxygenation and sickling, membrane damage occurs and cells become irreversibly sickled, and retain their abnormal shape even when full oxygenated. o With membrane damage water comes out of the cell resulting in intracellular dehydration ---> T MCHC. Due to membrane damage, sickle red cells become abnormally sticky --> responsible for microvascular occlusions. Remember o Irreversible sickle cells are responsible for hemolytic anemia. o Reversible sickle cells are responsible for vasoocclusive symptoms.