GP2 and Crohn disease: Crohn’s disease patients with penetrating disease (B3) demonstrated a significantly lower prevalence of anti-GP2 IgG alone and of anti-GP2 IgA and/or IgG [6/42 (14.3%) vs 42/127 (33.1%) and 7/42 (16.7%) vs 44/127 (34.6%); p < 0.02, p < 0.04, respectively] (Table 4).