A study noted that when compared with uninfected individuals, those with HIV infection and CD4 count < 200 cells/μL had a 44% increased risk of subsequent non-melanoma skin cancer (NMSC) overall and a 222% increase risk of squamous cell carcinoma (SCC) in particular, suggesting that subsequent SCC risk is associated with immune dysfunction, but melanoma was not mentioned similarly [5]. This evidence concerns the gene CD4 and immune system disorder.