Thus, chronic lesions in kidney biopsy have been recognized as an independent factor which predicts renal function and response to treatment in AAV/GN [24], while urinary excretion of molecules associated with interstitial fibrosis, such as IL-6, MCP-1 and recently, Dickkopf-related protein 3, PRO-C6 and C3M have been shown to be biomarkers of disease outcome [25–27]. This evidence concerns the gene DKK3 and anti-neutrophil cytoplasmic antibody-associated vasculitis.