However, the sensitivities of this test vary (14% vs. 51%) between active TB patients with and without HIV infection,22 and the sensitivity decreases gradually depending on the increase in the CD4+ count in the blood (39.0% with a CD4 count of <200 cells/μL, 51.7% with a CD4 count of <100 cells/μL, and 66.7% with a CD4 count of <50 cells/μL).23 This method is more significant in patients with a TB-HIV coinfection, so it is suitable for such a population in detection of trace levels of TB. The gene discussed is CD4; the disease is HIV infectious disease.