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We aimed to estimate the nature and prevalence of paroxysmal nocturnal hemoglobinuria (PNH) among Omani patients. We performed a retrospective review of all patients who were tested for PNH by flow cytometry at the Sultan Qaboos University Hospital, Muscat, between 2012 and 2019. Manifestations, treatment modalities, and outcomes were assessed. A total of 10 patients were diagnosed or were on follow-up for PNH (median age 22.5 years). Clinical manifestations included fatigue (80%) and anemia (70%). Six patients had classical PNH with hemolysis, three had PNH in the context of aplastic anemia, and one patient had subclinical PNH. The median total clone size (type II + III) for neutrophils was 95.5 (range: 1.5-97) (FLAER/CD24) and for monocytes was 91.6 (range = 0.04-99) (FLAER/CD14). Four patients had clone sizes > 50% at the time of diagnosis. The median follow-up period of the patients was 62 months (range = 8-204 months). One patient suffered thrombosis. Three patients were on immunosuppressant agents, five were initiated on eculizumab, and four had a bone marrow transplant. No deaths were reported in the cohort. The estimated average incidence of PNH among Omani patients was 1.5 per 5 000 000. PNH is rare in the Omani population. The predominant presentation is hemolytic anemia.
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INTRODUCTION: Stem cell enumeration by the hematopoietic progenitor cells (HPC) mode is a novel method available from Sysmex XN2000 hematology analyzer. A small amount of blood (190 µL) is required, and the results are available in a few minutes without manual gating or presample treatment. The present study compares stem cell measurements using XN2000 analyzer HPC mode and FC500 flow cytometry analyzer using peripheral blood (PB) specimens and apheresis products. METHODS: In this prospective study, CD34-positive cell counts were enumerated using an FC500 flow cytometry analyzer and compared with XN2000 Sysmex analyzer (XN-HPC mode) in the same samples. Results were compared using Bland-Altman plots. RESULTS: A total of 103 samples were used. In the PB samples, the median HPC count and CD34-positive cells were 83.5 × 106 /L and 78.0 × 106 /L, respectively. The mean Bland-Altman difference was 4.5 × 106 /L (Limits: -51.7 to 60.7 × 106 /L), with a Pearson's correlation of 0.79. In the apheresis products, the median HPC count and CD34-positive cells were 1468 × 106 /L (IQR: 1049 - 1960 × 106 /L) and 1327 × 106 /L (IQR: 910 - 2001 × 106 /L), respectively. The mean Bland-Altman difference was 179.0 × 106 /L (Limits: -2022.2 - 2380.2 × 106 /L), with a Pearson's correlation of 0.58. CONCLUSION: The XN-HPC mode has an excellent correlation and minimal disagreement for stem cell enumeration in PB compared with flow cytometry and could replace it. There is high disagreement in apheresis products, and therefore, the XN-HPC mode cannot be recommended.