Nod2 is well-documented as a critical mediator of host defense against infection from various bacteria (e.g., Listeria, Salmonella, and Staphylococcus)8 via its ability to sense the cell wall components peptidoglycan (PGN) and its derivative N-acetyl-muramyldipeptide (MDP)3. The gene discussed is NOD2; the disease is infection.