PRTN3 and anti-neutrophil cytoplasmic antibody-associated vasculitis: It can be found from the above classification criteria that patients with AAV are classified as having MPA easier if the present with the following characteristics: absence of sino-nasal symptoms or signs, lack of cytoplasmic ANCA or PR3-ANCA positivity, and an eosinophil count below 1 × 109/L.