Although a healthy orchestrated mucosal immune response involves B-cell maturation and development of IgA-secreting plasma cells directed toward more invasive strains of bacteria, anticommensal IgG can be found in patients with CD, which usually are absent in healthy controls.9, 10, 11 Although a single-cell sequencing study in therapy-refractory CD found an intestinal immune cell signature in inflamed areas that included IgG+ plasmablasts, rather than IgA+ plasmablasts,12 B-cell receptor (BCR) sequencing in CD has been limited to peripheral blood to date.13 Here, BCR is linked to Cowden disease.