Although the role that NOD2 signaling may play in the induction or pathogenesis of MS is less clear [7], the association between bacterial infections and MS as well as the detection of antigen presenting cells containing peptidoglycan, a source of NOD2 ligand, in the brains of MS patients support a possible pathogenic role for this PRR in MS [8]. The gene discussed is NOD2; the disease is myeloid sarcoma.