NEW INSIGHTS ON PAROXYSMAL NOCTURNAL HEMOGLOBINURIA (PNH)

Abstract

Paroxysmal nocturnal hemoglobinuria (PNH) is a I clonal, acquired hematopoietic stem cell disorder in which a somatic mutation of the x-linked PIG-A gene I results in a partial or absolute deficiency of all proteins linked to the cell membrane by the glycosyl I phosphatidylinositol (GPI) anchor (Takeda et al., 1993).

Most, if not all patients with PNH have evidence I of underlying bone marrow failure. In addition, up to 50% of patients with aplastic anemia go on to develop a I PNH clone. Thus there is a very close association between aplastic anemia and PNH. The successful use of immunosuppressive therapy for treatment and control of aplastic anemia provides strong evidence that there may be an immunological component to the I disease and it appears that this promotes the development of PNH clones (Paquette et al., 1997). I The most profound clinical feature ofPNH is a

I hemolytic anemia due to a deficiency from the red blood cell (RBC) membrane of the complement I regulatory molecules CD55 (decay accelerating factor [DAF]) and CD59 (membrane inhibitor of reactive lysis