Overall, most of the studies reported significant differences (P = 0.0001) in CgA cell density in all types of patients with IBS compared with controls, except for Mazzawi and colleagues 8 in ileum (P = 0.9819) and El-Salhy et al12 in all parts of the colon (P = 0.5260). This evidence concerns the gene CGA and irritable bowel syndrome.