This pivotal role of GCC signaling in intestinal fluid balance is most poignantly illustrated by gain- and loss-of-function mutations in GUCY2C (encoding GCC), which have been shown to cause secretory diarrhea and intestinal obstruction, respectively (Romi et al. 2012; Fiskerstrand et al. 2012; Muller et al. 2015). This evidence concerns the gene GUCY2C and Secretory diarrhea.