HMG-CoA synthase 1 (Hmgcs1) and HMG-CoA reductase (Hmgcr), which are involved in cholesterol synthesis, are downregulated in the liver of sterile mice, so there is the lack of intestinal microbiota bile acid synthesis in hypercholesterolemia mice [14]. This evidence concerns the gene HMGCR and familial hypercholesterolemia.