CD4 and acute lymphoblastic leukemia: In the last few years, studies targeting HIV-1 co-receptor CCR5 using CRISPR-Cas9 have made significant progress, such as CCR5 disruption in induced pluripotent stem cells (Kang et al., 2015), inducing CCR5 Δ32/Δ32 homozygotes in CD4+ Jurkat cells and primary CD4+ cells (Qi et al., 2018), and even CCR5-Edited stem cells in a patient with HIV-1 and acute lymphocytic leukemia (Xu et al., 2019).