Elevated or persistently positive ANCA titers as an indicator of disease activity or relapse in patients with AAV remains controversial (42, 43), and commonly measured laboratory markers, such as absolute eosinophil count, serum IgE, erythrocyte sedimentation rate, and C-reactive protein, have limitations as biomarkers of disease activity or predictors of flare in patients with EGPA (44). This evidence concerns the gene IGHE and anti-neutrophil cytoplasmic antibody-associated vasculitis.