To overcome this limitation, we constructed a metric to quantify the relative reduction in the CD4 cell count, R, corresponding to the absolute CD4 count, T, as R=Thealthy-TThealthy-TAIDS× 100=ΔCD4ΔCD4AIDS×100, where Thealthy was the count pre-infection and TAIDS = 200 cells/μL the count defining AIDS. This evidence concerns the gene CD4 and AIDS.