However, some data showed that mutations of TLR4 (Asp299Gly and Thr399Ile) in human leucocyte antigen (HLA)-matched sibling patients contributed to a reduced risk of GVHD, but an increased incidence for Gram-negative bacteremia tended to occur in HSCT patients with such TLR4 mutations [26]. Here, TLR4 is linked to graft versus host disease.