At the same extent, the ANCA pattern is usually different in these two clinical entities, with patients with EGPA being seronegative in up to 50% of cases and presenting with anti-MPO while patients with GPA more frequently show c-ANCA, anti-proteinase (PR)-3 antibodies [5, 6]. This evidence concerns the gene PRTN3 and eosinophilic granulomatosis with polyangiitis.