Granulomatosis with polyangiitis (GPA) may mimic particular aspects of EGPA, especially in those patients, which present peripheral eosinophilia, the ANCA specificity (cANCA PR3-specific, in GPA) and the presence, in GPA, of pulmonary cavitated nodules associated with nasal crusting and nasal and paranasal sinuses erosion, allow clinicians to differentiate the two vasculitides. The gene discussed is PRTN3; the disease is Increased total eosinophil count.