What is PNH?

PNH (paroxysmal nocturnal hemoglobinuria) is a rare and serous blood disease that causes your red blood cells to break apart. PNH occurs because of a genetic change to some of your blood-forming stem cells. These defective stem cells become PNH blood cells that are missing an important coating that protects them from your immune system. If you have PNH, there will be times where your immune system destroys many of your red blood cells very quickly. This causes low red blood cell counts. This can also cause blood clots, muscle spasms and dark urine.