Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired clonal hematopoietic stem cell disorder caused by phosphatidylinositol N-acetylglucosaminyltransferase subunit A (PIG-A) gene mutations, leading to complement-mediated hemolysis, cytopenias, and thrombotic risk. This evidence concerns the gene PIGA and paroxysmal nocturnal hemoglobinuria.