When ART was additionally made available to HIV infected individuals with a CD4+ cell count between 350 and 500 cells per milliliter (assuming an ART coverage equal to that of individuals with a CD4+ cell count ≤ 350) the percentages of TB and HIV cases and deaths averted (including drug susceptible, MDR, and XDR-TB) were doubled (S4 Fig). The gene discussed is CD4; the disease is tuberculosis.