CCR5 and graft versus host disease: The donor was chosen specifically for homozygosity for the CCR5 Δ32 allele, and thus without a functional CCR5 coreceptor and resistance to HIV infection; as a result, after two stem cell transplantations, graft-versus-host disease, irradiation, immunosuppressive therapies and whole body irradiation, the Berlin patient presented with a drug-free HIV remission [343] which lasted for 12 years prior to his death.