HLA-G and graft versus host disease: Because genetic polymorphism in the untranslated or promoter region may regulate the levels of HLA-G gene expression and alter the status of immune response and the magnitude of immune tolerance, the SNPs and haplotypes locate in the 3’-UTR and 5’-URR were selected in this study to define whether these SNPs and haplotypes are associated with the mortality, the risk of relapse, and the development of GVHD for patients receiving HSCT.