This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Platelet, Subject name: Pathology
Ham test is done for detection of which of the following? 
Select and explain. 
A. Ankyrin defect, B. GPI-linked protein defect, C. Spectrin defect, D. Mannose binding protein defect
B: GPI-linked protein defect
Answer: B: GPI-linked protein defect 
Explanation: Ham test (Acidified serum lysis test) This is the screening test for PNH Used to detect cells deficient in CD59 CD55 and CD59 are GPI-linked proteins which are defective in PNH due to acquired somatic mutation in PIGA gene located on X chromosome Acidification of serum activates complement alternate pathway and causes haemolysis of red cells if they are abnormally sensitive to complement Flow cytometry (FLAER) test is used to as confirmatory test for PNH