Case Report: Proteinase 3 Antineutrophil Cytoplasmic Antibody-Associated Ulcerative Colitis Presenting as Recurrent Intestinal Pseudo-Obstruction in a Teenage Patient With <i>in situ</i> Proteinase 3 Immunohistochemical Staining. The gene discussed is PRTN3; the disease is intestinal pseudo-obstruction.