This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hemolytic Anemias: Basic concepts and classification, Subject name: Pathology
[{'content': 'Microangiopathic hemolytic anaemia (MAHA) is a component of all of the following, except: \nSelect and explain. \nA. Thrombotic thrombocytopenic purpura (TTP), B. Hemolytic uremic syndrome (HUS), C. Hemolysis with elevated liver enzymes and low platelet (HELLP) syndrome, D. Paroxysmal nocturnal hemoglobinuria', 'role': 'user'}, {'content': 'Answer: D \nExplanation: - Paroxysmal nocturnal hemoglobinuria (PNH): Results from acquired mutations in PIGA gene leading to deficiency of GPI-linked proteins in membrane of blood cells. Red cells deficient in GPI-linked factors are abnormally susceptible to lysis or injury by complement. This manifests as intravascular hemolysis, which is caused by the C5b-C9 membrane attack complex. The hemolysis is paroxysmal and nocturnal in only 25% of cases; chronic hemolysis without dramatic hemoglobinuria is more typical. Other options: - TTP : characterized by pentad of Microangiopathic haemolytic anemia; Thrombocytopenia; Fluctuating neurologic dysfunction; Renal abnormalities & Fever. - HUS is characterized by triad of acute renal failure, thrombocytopenia & microangiopathic hemolytic anemia. - HELLP syndrome : The main three diagnostic criteria include : Hepatic dysfunction thrombocytopenia microangiopathic hemolytic anaemia in patients suspected to have preeclampsia.', 'role': 'assistant'}]