Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematopoietic stem cell disorder characterized clinically by occasional, hemoglobinuria producing a classically dark urine usually occurring in the night or morning.
Hemolytic anemia, pancytopenia, and thrombophilia with a tendency to thrombosis are further features of the disease. The combination, severity, and timing of these symptoms can be very variable. The disease mainly affects young adults and the disease peak is between 25 and 45 years of age with a balanced gender relationship.
A familial history has not yet been observed. The cause of PNH is acquired somatic mutations in the PIG-A gene. This encodes an enzyme involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor. The mutation occurs in one or more hematopoietic cells and results in complete or partial loss of all proteins anchored in the cell membrane via GPI. Most important are CD55 and CD59, which protect the cell from the cancerous complement system. Due to the lack of protective factor of the cell membrane, the enzyme defect causes intravascular lysis.
The prognosis is determined by the frequency and severity of hemolytic crises and thromboses and by the extent of the disease. of bone marrow depression. Up to 35% of patients die within 5 years of diagnosis. Common causes of death are thrombosis, bleeding, infections resulting from bone marrow depression or kidney failure.