This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Paroxymal noctural hemoglobinuria is due to - \nSelect and explain. \nA. Acquired red cell defect, B. Congential red cell defect, C. Auto immune defect, D. Lead poisoning', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Paroxysmal Nocturnal hemoglobinuria (PNH).\n\nPNH is the only hemolytic anemia caused by an acquired intrinsic defect in the cell membrane.\nPNH results from an acquired mutation that inhibits the synthesis of Glycosylphosphatidylinositol (GPI).\nSeveral protective proteins called complement-regulating proteins are anchored to the cell membrane by GPI.\nThese protective proteins prevent activation of complement and thereby complement-mediated lysis of blood cells.\nDeficiency of GPI results in absence of these proteins and blood cells become unusually sensitive to complement-mediated lysis.\nThe GPI - linked proteins that are missing are : -\nInhibitor of reactive lysis (CD-59) → Their absence results in hemolysis\nDecay-accelerating factor (CD 55) → Their absence results in hemolysis\nC8 binding protein.\xa0→\xa0Their absence results in hemolysis\nUrokinase plasminogen activator receptor - Its absence promotes thrombosis.\nLeukocyte alkaline phosphatase (LAP) → Decreased LAP score.\nBecause 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 \xa0- Anemia, Leucopenia, Granulocytopenia, Thrombocytopenia', 'role': 'assistant'}]