HIV/AIDS was first described in 1981 (Centers for Disease Control, 1981; Gottlieb et al., 1981), and CD4 was soon identified as the main receptor for viral entry into CD4+ T cells (Dalgleish et al., 1984; Klatzmann et al., 1984; Maddon et al., 1986), the predominant host cells for HIV (Wilen et al., 2012). The gene discussed is CD4; the disease is AIDS.