For instance, a GWAS performed for CH4 yield and gross CH4 in sheep identified two significant markers harboring the candidate genes Tetraspanin 14 (TSPAN14) which has been significantly associated with inflammatory bowel disease in human (Jostins et al., 2013) and Peroxisomal Biogenesis Factor 2 (PEX2) which is hypothesized to be important to lipid metabolism and fatty acid oxidation in cattle (Mach, 2013; Rowe et al., 2014). This evidence concerns the gene PEX2 and inflammatory bowel disease.