Paroxysmal nocturnal hemoglobinuria and the glycosylphosphatidylinositol anchor.

Although the clinical syndrome of paroxysmal nocturnal hemoglobinuria (PNH)' was recognized many years ago ( 1 ), its complexity was difficult to explain. The erythrocytes were known to be susceptible to the hemolytic action of comple- ment, and this characteristic formed the basis for the diagnosis of the disease (2). In addition, many patients suffered thromboses and/or had evidence of relative or absolute diminution in hematopoiesis (3). Although the disease appeared to be acquired, no specific lesion could be delineated which could account for the complex clinical symptoms.