Paroxysmal nocturnal hemoglobinuria clones in children with acquired aplastic anemia: a multicentre study.

A multicentre study evaluating the presence of glycosil phosphatidyl-inositol(GPI)- negative populationswas performed in 85 children with acquired aplastic anemia(AA). A GPI- negative populationwas observed in 41% of patients at diagnosis, 48% during immune-suppressive therapy (IST), and 45% in patients off-therapy. No association was found between the presence of a GPI- negative populationat diagnosis and the response to IST. In addition, the response rate to IST did not differ between the patients who were GPI-positive at diagnosis and later developed GPI- negative populationsand the 11 patients who remained GPI-positive. Two patients with a GPI- negative population>10%, and laboratory signs of hemolysiswithout hemoglobinuriawere considered affected by paroxysmal nocturnal hemoglobinuria(PNH) secondary to AA; no thrombotic event was reported. Excluding the 2 patients with a GPI- negative populationgreater than 10%, we did not observe a significant correlation between LDH levels and GPI- negative populationsize. In this study monitoring for laboratory signs of hemolysiswas sufficient to diagnose PNH in AA patients. The presence of minor GPI- negative populationsat diagnosis in our series did not influence the therapeutic response. As occasionally the appearance of a GPI- negative populationwas observed at cyclosporine (CSA) tapering or AA relapse, a possible role of GPI- negative populationmonitoring during IST modulation may need further investigation.