Interestingly, our and others’ functional studies uniformly indicate that antibodies recognizing the cluster A region are able to induce cytolysis of gp120-coated target cells (1, 2, 9, 10) and HIV-infected cells which retain CD4 at their surface or are triggered by CD4 mimetics (17, –, 21), confirming their potential for therapeutic or preventative treatment of HIV-1 infection. The gene discussed is CD4; the disease is HIV-1 infection.