In the early 2000s, a multicenter, randomized, double-blind, placebo-controlled trial of fluconazole for primary cryptococcal meningitis prophylaxis in HIV-infected patients with a CD4+ T-cell count < 100 cells/μL showed that patients in the placebo group were 4.3 times more likely to die than those in the fluconazole group [85]. The gene discussed is CD4; the disease is Cryptococcal meningitis.