Viera Fábryová
Paroxysmal nocturnal haemoglobinuria (PNH) is the only haemolytic anaemia caused by an acquired abnormality and 30 % of cases arise from severe aplastic anaemia or myelodysplastic syndrome. The lesion results from a clonal somatic mutation of an X chromosome gene, phophatidylinositol glycan class A (PIGA) that occurs at the pluripotential stem cell level. The abnormality is well-defined as the absence of glycosyl phosphatidylinositol anchor (GPI) and two important complement inhibitory proteins in the membrane: decay accelerating factor (DAF, CD55) and membrane inhibitor of reactive lysis (MIRL, CD55). Haemosiderinuria is a constant feature of PNH, anaemia is mild to severe, patients are predisposed to thrombosis. The treatment is mainly supportive, with transfusions, antibiotics, anticoagulants. A new approach to the therapy is a monoclonal antibody eculizumab.