SLC6A8 and Crohn disease: Since the CK/PCr system, as well as the creatine transporter (CrT1) are involved in a plethora of processes that are important for cellular energetics [3,8], also in intestinal epithelial cells [16,17,62] it is interesting that the investigation of mucosal biopsied from 30 patients with Crohn’s disease and 27 patients with ulcerative colitis both showed lower expression levels of CrT1, which might contribute to the reduced barrier function of intestinal epithelium [14] (see Figure 3).