However, subsequent studies indicated that MPO-ANCA levels were associated with relapses, particularly in patients with AAV-GN.15,19, –21 Taken together, serial determinations of ANCAs might be of interest for guiding remission-maintenance treatment strategies in patients with AAV-GN, particularly in MPO-ANCA–associated vasculitis with GN. This evidence concerns the gene MPO and ganglioneuroma.