<b>Conclusions</b>: This case provides additional documentation of an uncommon overlap between PR3-ANCA-associated vasculitis and MGUS in a Latin American patient and highlights the role of renal biopsy in distinguishing MGRS from pauci-immune vasculitis in the presence of paraproteinemia. This evidence concerns the gene PRTN3 and anti-neutrophil cytoplasmic antibody-associated vasculitis.