The most prominent examples include Timothy Ray Brown, the “Berlin Patient,” and the “London Patient,” both of whom received allogeneic hematopoietic stem cell transplants from donors carrying the homozygous CCR5-Δ32 mutation, a naturally occurring 32-base pair deletion in the CCR5 gene that renders the CCR5 receptor nonfunctional and confers resistance to HIV-1 infection [115,116]. This evidence concerns the gene CCR5 and HIV-1 infection.