TDF-induced renal toxicity is more likely to occur in HIV patients with preexisting kidney disease or poorly controlled HIV disease with longer overall antiviral treatment duration, older age, elevated baseline creatinine concentration, female gender, African American ethnicity, CD4 nadir <200 cells/mm3, and concomitant administration of other nephrotoxic drugs [29, 30]. The gene discussed is CD4; the disease is kidney disorder.