The loss of CD4+ T cells in HIV infection correlated with susceptibility to a large number of infectious agents including viruses, bacteria, fungi, and parasites, which are life-threatening in untreated patients (Gottlieb et al., 1981; Masur et al., 1981; Small et al., 1983; Vieira et al., 1983). The gene discussed is CD4; the disease is HIV infectious disease.