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CCR5 sits on the surface of immune cells as part of normal signalling. HIV exploits it as a handle to grab and enter the cell. About one per cent of people of northern European ancestry are born with both copies deleted and are largely resistant to HIV while appearing otherwise healthy — which is why disabling it has been studied as an HIV treatment, and why it was the gene He Jiankui edited in human embryos in 2018.
CCR5, at 3p21.31, encodes a chemokine receptor serving as the principal co-receptor for R5-tropic HIV-1. The CCR5-Δ32 deletion, homozygous in roughly 1 per cent of people of northern European ancestry, confers substantial resistance. Somatic disruption has been pursued clinically since 2009. It was the target of the 2018 embryo editing that produced the first gene-edited children — where the edits were mosaic and did not reproduce Δ32, and where the germline nature of the change made the act indefensible.
Sources
- New England Journal of Medicine (Tebas et al.) · 2014
Gene editing of CCR5 in autologous CD4 T cells of persons infected with HIV ↗