In multivariate analysis, the only factor that was statistically significantly associated with serological response at 6 months of follow-up was age less than 34 years (adjusted odds ratio [OR], 1.96; 95% confidence interval [CI], 1.247–3.080; P = 0.004), while the associations between secondary syphilis (adjusted OR, 1.499; 95% CI, 0.943–2.383; P = 0.087) and CD4 <350 cells/μl (adjusted OR, 0.672; 95% CI, 0.425–1.065, P = 0.091) and serological response were of borderline significance (Table 3). The gene discussed is CD4; the disease is syphilis.