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: Medicine
PNH patients will be having deficient surface proteins that normally protect the red cells from activated compliments. What are the two deficient surface proteins? 
Select and explain. 
A. CD 45 and CD 59, B. CD 51 and CD 59, C. CD 55 and CD 59, D. CD58 and CD 59
C: CD 55 and CD 59
Answer: C: CD 55 and CD 59 
Explanation: The definitive diagnosis of PNH is based on the demonstration that a substantial propoion of the patient's red cells have an increased susceptibility to complement (C), due to the deficiency on their surface of proteins (paicularly CD59 and CD55). Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 884