CD59 is a type of glycoprotein that is produced by CD59 gene in humans. Any mutation to this gene will result in rapid destruction of red blood cells, leading to PNH which is Paroxysmal Nocturnal Haemoglobinuria. PNH is an acute disorder with mortality rate of around 50%. To detect PNH, Flow Cytometry is used with CD59 antigen. Flow Cytometry is a method of counting number of RBCs and properties of cells like cell size, granularity etc. Just by examining these properties it becomes easy to detect any abnormality in the blood cells.