True about Sickle cell anemia except -

Sickle cell anemia is due to a point mutation (not deletion) that leads to substitution of valine for glutamic acid at sixth position of the β-globin chain. SCA occurs more commonly in black people from parts of Sub-Saharan Africa----------- Internet. Effect of HbS on RBCs In deoxygenated condition, the HbS molecules undergo polymerization and aggregation. With continued deoxygenation, aggregated HbS molecules assemble into long needle-like fibers within red cells, producing a distorted sickle or holly-leaf shape. Sickling of red cells is reversible initially, i.e., with oxygenation, HbS depolymerizes and cell shape normalizes. 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. With membrane damage, water comes out of the cell resulting in intracellular dehydration →↑ MCHC. Due to membrane damage, sickle red cells become abnormally sticky → responsible for microvascular occlusions. Remember Irreversible sickle cells are responsible for hemolytic anemia. Reversible sickle cells are responsible for vasoocclusive symptoms.