title: Flow cytometry screening for paroxysmal nocturnal hemoglobinuria: A single-center experience in Saudi Arabia.
abstract: BACKGROUND
  Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematopoietic stem cell disorder, characterized by the deficiency of glycosylphosphatidylinositol (GPI) that anchors proteins in cell membranes. PNH is manifest variously with hemoglobinuria, thrombosis, or bone marrow failure. This retrospective study was aimed at assessing the incidence and characteristics of patients diagnosed with PNH in the King Fisal Specialist Hospital and research center.
  
  
  METHODS
  Patients referred for PNH diagnosis at King Faisal Specialist Hospital and Research Centre, Riyadh, during the 2-year period (2012-2013) were included in the analysis. Peripheral blood samples were used for multi-parametric flow cytometry analysis based on fluorescent inactive aerolysin (FLAER), and the markers, CD235a and CD59 on red blood cells (RBCs), and CD14, CD45, CD64, CD24, and CD15 on white blood cells (WBCs) exclusively monocytes and granulocytes. Univariate analysis of the disease characteristics was performed.
  
  
  RESULTS
  Of the 366 samples submitted for PNH screening, 14 were positive (4%) and 11 were evaluable. Of the 11 patients analyzed, 8 patients (73%) presented with aplastic anemia, 1 patient (9%) each with pancytopenia, Budd-Chiari syndrome, and immune thrombocytopenia purpura. All samples showed type II and III GPI-deficient clones with a median clone size of 15% (range, 0.7%-56%) in the RBCs, and 63% (range, 3.8%-100%) in WBCs (monocytes and granulocytes).
  
  
  CONCLUSIONS
  This study confirms the rarity of PNH and its predominant presentation as aplastic anemia or thrombosis in a Saudi Arabian population, similar to the worldwide incidence.
authors: Pathology Department, College of Medicine, Qassim University, Qassim, Saudi Arabia.
authors: Nahlah
authors: N
authors: AlGhasham
authors: Pathology Department, Hematology Section, King Khalid University Hospital, Riyadh, Saudi Arabia.
authors: Yasmeen
authors: Y
authors: Abulkhair
authors: Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors: Salem
authors: S
authors: Khalil
mesh_terms: D000328:Adult; D000741:Anemia, Aplastic / Q000175:diagnosis* / Q000276:immunology; D001853:Bone Marrow / Q000276:immunology; D004912:Erythrocytes / Q000166:cytology*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006098:Granulocytes / Q000166:cytology*; D006457:Hemoglobinuria, Paroxysmal / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D007962:Leukocytes / Q000166:cytology* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D012189:Retrospective Studies; D012529:Saudi Arabia
keywords: PNH; aplastic anemia; paroxysmal nocturnal hemoglobinuria; thrombosis