Do you recommend giving anti-complement therapy to a patient with approximately 20% PNH clones who has severe aplastic anemia but no other risks for thrombosis or hemolysis?   

Depends on the age, the extent of hemolysis, dynamics of PNH clone over time, marrow findings and HSCT donor availability, and also if the patient responds to IST.  If the patient has poor response to IST, good donor availability, and no severe hemolysis, I would go straight to transplant. If ...