MPO and eosinophilic granulomatosis with polyangiitis: This group includes Microscopic Polyangiitis (MPA), Eosinophilic Granulomatosis with Polyangiitis (EGPA), both associated with p-ANCA and anti-MPO positivity, and Granulomatosis with Polyangiitis (GPA), which is associated with the presence of c-ANCA and anti-PR3.