Mucosal soluble mediators such as proinflammatory cytokines [e.g., tumor necrosing factor-α (TNF-α), interleukin 6 (IL-6)], and luminal factors in patients with IBS decrease transepithelial electrical resistance (TEER) of intestinal epithelial cells and increase paracellular permeability to macromolecules (13). The gene discussed is TNF; the disease is irritable bowel syndrome.