In addition to IBD, TNFSF15 gene polymorphism rs4263839 is associated with susceptibility to irritable bowel syndrome and ankylosing spondylitis in Caucasians [52, 53], and we recently found that TNFSF15 gene polymorphism rs4979462 is associated with susceptibility to PBC in a Japanese population [54]. This evidence concerns the gene TNFSF15 and irritable bowel syndrome.