KDELR2 and irritable bowel syndrome: Genome-wide association (GWA) studies amongst others have led to the elucidation of specific genetic alterations in IBS such as Nav1.5 (385), GPBAR1 (G protein-coupled bile acid receptor 1) (386), KDELR2 (KDEL endoplasmic reticulum protein retention receptor-2) and GRID2IP [glutamate receptor, ionotropic, delta 2 (Grid2) interacting protein] (381), NXPH1 (neurexophilin 1), and CDC42 (cell division control protein 42 homolog) (387).