PRTN3 and eosinophilic granulomatosis with polyangiitis: There are reports about increased IgG4 levels in some vasculitides, especially in eosinophilic granulomatosis with polyangiitis (EGPA)—formerly known as Churg-Strauss syndrome—and in granulomatosis with polyangiitis (GPA), associated with anti-neutrophil cytoplasmic antibodies (c-ANCA).