ArticlesParoxysmal nocturnal haemoglobinuria: long-term follow-up and prognostic factors
Introduction
Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired chronic haemolytic anaemia, often associated with recurrent nocturnal exacerbations, neutropenia, thrombocytopenia, and episodes of venous thrombosis.1, 2 The biological distinguishing characteristic of PNH cells is the deficiency in several types of cell-surface proteins, which have the common structural feature of being anchored to the cell surface by a glycosyl-phosphatidylinositol (GPI) moiety.3 A gene, PIG-A, has been identified by expression cloning,4, 5 somatic molecular alterations of which cause the defect in GPI-anchored proteins in all PNH patients studied so far.7
The clinical course of PNH is highly variable.2 Although allogeneic bone-marrow transplantation is the only available curative therapy for PNH,2, 7, 8, 9 this procedure is itself associated with substantial morbidity and mortality. Advances in the knowledge of the molecular mechanisms of PNH have raised the possibility of a gene therapy approach. However, most of the reported clinical studies were based on a limited number of patients. Because the disease is so rare there are still no prognostic criteria to define indications for intensive therapeutic measures. Our study, of the largest group of patients with PNH to date, aimed to describe the long-term outcome of the disease and to search for prognostic factors that affect survival.
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Patients and methods
The population of patients consists of two parts. Data on some of the first group were reported in 1985.10 From this group (1950–81) we decided to include patients who met the following criteria: a positive Ham's test reported by a physician from a French centre and demographic data available to allow clinical follow-up. The second source of data was from a questionnaire sent to all members of the French Society of Haematology in November, 1994, which requested information on all patients with
Results
The median age at presentation was 33 years (range 6-82). Initial biological and clinical symptoms are summarised in table 1. Among the 204 (93%) patients with peripheral blood abnormalities 196 had anaemia (median haemoglobin concentration [known in 189 patients] 80 g/L [range 4–12]), 90 patients had neutropenia (absolute neutrophil count [known in 218 patients], of 0·9×109L [0·1–1·5], and 112 had thrombocytopenia (platelet count [known in 219 patients], 0·4×1011/L [0·01–1·35]).
Red-blood-cell
Discussion
This retrospective study involved 220 patients with PNH diagnosed in France between 1950 and 1995, the largest number in any published study. As far as we know, no previous study7, 8, 9, 11, 16, 17, 18, 19, 20, 21, 22, 23 provided statistical estimates of prognostic criteria, mainly because of the rarity of the disease. The demographic data of our patients are similar to those of other large studies.11, 18, 19 PNH is mainly a disease of adults, however, as described by Ware and colleagues,22
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