They concluded that a high-serum titer (>1:64) in TRUST is a neurosyphilis predictor among all participants (HIV-positive and HIV-negative); being ≥50 years old in those who were HIV-negative is another predictor to develop neurosyphilis; and fewer than 300 CD4+ T cells/μL is a predictor of asymptomatic neurosyphilis in HIV-positive participants. This evidence concerns the gene CD4 and neurosyphilis.