The distinction between different AAVs based on ANCA patterns is far from perfect; PR3-ANCAs were present in about two-thirds of patients with GPA but also in one-quarter of patients with MPA, whereas MPO-ANCAs were in the majority of patients with MPA but also in up to one-quarter of patients with GPA [136]. The gene discussed is PRTN3; the disease is granulomatosis with polyangiitis.