STANDARDIZATION OF FLOW CYTOMETRIC DIAGNOSIS IN PAROXYSMAL NOCTURNAL HEMOGLOBINURIA : A NATIONAL CONSENSUS STATEMENT

AbstractIntroduction : Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder caused by an acquired somatic mutation in the PIGA gene. This mutation leads to a deficiency in the synthesis of glycosylphosphatidylinositol (GPI) anchors, which are essential for tethering various proteins to the cell surface. Key among these are the complement regulatory proteins CD55 and CD59, which normally inhibit the assembly of the membrane attack complex (MAC). The absence of these GPI-anchored proteins results in uncontrolled intravascular hemolysis. Consequently, multiparametric flow cytometry has become the gold standard for identifying and quantifying GPI-deficient cell populations.Methods: During the 4th PNH Workshop held in June 2010, the Algerian Flow Cytometry Group (GAC) established a national consensus regarding the clinical indications and technical procedures for PNH clone detection. A secondary review and refinement phase were conducted to ensure the definitive validation of the standardized protocol.Results: This workshop defined and standardized several critical components of PNH diagnostics: clinical inclusion criteria for immunophenotyping, standardized request forms, acquisition protocols, gating strategies, and the formal structure of flow cytometry reporting.Conclusion: This consensus document serves as the primary reference for diagnostic laboratories utilizing flow cytometry for PNH, ensuring harmonized and high-sensitivity detection across institutions.Keywords: flow cytometry, paroxysmal nocturnal hemoglobinuria, protocol harmonization, PIGA mutation, GPI-anchor.