Organ damage in EGPA patients can occur with two different mechanisms: as a consequence of either vasculitis leading to ischemic effects and inflammation, which is prominent in myeloperoxidase anti-neutrophil cytoplasmic antibodies (MPO-ANCA)-positive patients, or either eosinophil-associated vascular occlusion leading to ischemia and eosinophil-associated tissue damage, which is frequent in MPO-ANCA-negative patients (4). This evidence concerns the gene MPO and vasculitis.