In support of this hypothesis, recent studies have suggested a potential association between IBS and elevated ALT and metabolic syndrome,49 and the association of a high degree of nonalcoholic fatty liver with an increased risk of IBS.50 In support of this hypothesis, Chen et al. demonstrated that C. aerofaciens may significantly decrease the expression of zonula occludens-1 (ZO-1),45 a tight junction protein also demonstrated to control endothelial adherens junctions.51 This evidence concerns the gene GPT and irritable bowel syndrome.