Between ages 4 and 9 months, Nppb−/− females developed PAN-like mesenteric vasculitis, commonly with intestinal necrosis or colitis (Fig. 3A, right panel, Fig. 3B, indicated by green lines) and multiple mesenteric aneurysms (Fig. 3A–C, indicated by blue arrows). The gene discussed is NPPB; the disease is colitis.