Mutation

Any change or alteration in a gene. A mutation may cause disease or may be a normal variation. Paroxysmal nocturnal hemoglobinuria Paroxysmal nocturnal hemoglobinuria: (par-uk-SIZ-muhl nok-TURN-uhl hee-muh-gloe-buh-NYOOR-ee-uh) A rare and serious blood disease that causes red blood cells to break apart. Paroxysmal means sudden and irregular. Nocturnal means at night. Hemoglobinuria means hemoglobin in the urine. Hemoglobin is the red part of red blood cells. A… (PNH) occurs because of a mutation in the PIG-A gene PIG-A gene: The gene that is in charge of making a protective shield of proteins on normal red blood cells. Paroxysmal nocturnal hemoglobinuria (PNH) occurs because of a change (mutation) in the PIG-A gene of a single stem cell in the bone marrow. of a single stem cell in the bone marrow bone marrow: The soft, spongy tissue inside most bones. Blood cells are formed in the bone marrow. .