Immunity-related GTPase family M protein (IRGM) is essential for clearance of severe protozoan and bacterial infections. IRGM belongs to the p47 immunity-related GTPase family. IRGM serves in innate immune response possibly via regulation of autophagy. IRGM regulates proinflammatory cytokine production and inhibit endotoxemia upon infection and also has a part in macrophages adhesion and motility. Polymorphisms which modify the natural expression of the IRGM gene are associated with a susceptibility to Crohn’s disease and tuberculosis.