Some of these factors include: female sex[5,9,10,19], increasing age[7,8], high HIV viral load[6,8,20], low CD4 cell count[5-10,12-14,20], presenting opportunistic infections (clinical AIDS)[5,6,20], low body mass index (BMI)[7,10,14] and intravenous drug use[5]. This evidence concerns the gene CD4 and AIDS.