Paroxymal noctural hemoglobinuria is due to ?

Ans. is 'a' i.e., Acquired red cell defect Paroxysmal Nocturnal hemoglobinuria (PNH). o PNH is the only hemolytic anemia caused by an acquired intrinsic defect in the cell membrane. o PNH results from acquired mutation that inhibits the synthesis of Glycosylphospatidylinositol (GPI). Several protective proteins called complement regulating proteins are anchored to cell membrane by GPI. These protective proteins prevent activation of complement and there by complement mediated lysis of blood cells. Deficiency of GPI results in absence of these proteins and blood cells become unusually sensitive to complement mediated lysis. o The GPI - linked proteins that are missing are : - Inhibitor of reactive lysis (CD-59) Decay accelerating factor (CD 55) Their absence results in hemolysis C8 binding protein. Urokinase plasminogen activator receptor - Its absence promotes thrombosis. Leukocyte alkaline phosphotase (LAP) Decreased LAP score. o Because the causative somatic mutations occur in pluripotent stem cells, all its clonal progeny i.e., red cells, white cells, and platelets are deficient in GPI linked protein. So, all these cells are sensitive to complement mediated lysis that results in : - - Anemia, Leucopenia, Granulocytopenia, Thrombocytopenia