While AAV traditionally comprises three subtypes, including eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome), granulomatosis with polyangiitis (Wegener’s granulomatosis), and microscopic polyangiitis [2], it has recently been categorised into three subtypes according to ANCA types as myeloperoxidase-ANCA, proteinase 3-ANCA, and ANCA-negative vasculitis [1,3]. The gene discussed is MPO; the disease is granulomatosis with polyangiitis.