NOD2 and Crohn disease: The NOD2 or CARD15, the first gene associated to Crohn’s disease (CD), is an intracellular receptor of the Nod Like Receptor (NLR) family that binds to muramyl-dipeptide (MDP), the minimal bioactive component of bacterial peptidoglycan [4], and through Nuclear Factor κB (NF-κB) pathway, it regulates the expression of tumor necrosis factor (TNF) and other pro-inflammatory cytokines [5].