Furthermore, CCR5 antagonists reduce HIV-1 replication and a delta-32 mutation in the CCR5 receptor renders CD4+ T cells resistant to CCR5-tropic HIV infection (Dean et al., 1996; Liu et al., 1996; Samson et al., 1996b; Dorr et al., 2005; Fätkenheuer et al., 2005; Gulick et al., 2008). The gene discussed is CD4; the disease is HIV infectious disease.