This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
Intrinsic cell wall defect of RBCs is feature of - 
Select and explain. 
A. Paroxysmal nocturnal hemoglobinuria, B. Sickle cell anemia, C. Hemophilia, D. All of the above
A: Paroxysmal nocturnal hemoglobinuria
Answer: A: Paroxysmal nocturnal hemoglobinuria 
Explanation: Paroxysmal nocturnal hemoglobinuria is a disease that results from acquired mutations in the phosphatidylinositol glycan complementation group A gene (PIGA), an enzyme that is essential for the synthesis of ceain membrane associated complement regulatory proteins. Ref :Robbins pathologic basis of disease ; south east asia edition ;pg:642