Paroxysmal nocturnal haemoglobinuria
Paroxysmal nocturnal haemoglobinuria is a rare disorder with a minimum prevalence estimated to 1-1.5 cases per million. It is an acquired disorder of the bone marrow stem cell characterized by the lack of some molecules, normally attached to the cell membrane. The molecular defect causing the disease arises at the haematopoietic stem cell and consists in somatic mutations of a gene called PIG-A. Defective GPI anchor causes the loss of surface proteins and allow complement lysis. The clinical manifestations which are variable are intravascular haemolytic anaemia, venous thrombosis, and decreased number of blood cells due to deficient production of the bone marrow (cytopenia). The diagnosis is established by demonstrating the deficiency of blood cell membrane proteins. The disorder often arises in the setting of aplastic anaemia. Treatment is primarily symptomatic or includes, in severe cases, bone marrow transplantation.
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