HTLV-I infection plays a role in the cellular transformation and tumorigenesis of CD4+ T-lymphocytes into adult T-cell leukemia/lymphoma cells [41]; base-excision repair induces the proliferation of prostate cancer [42]; and primary immunodeficiency is related to malignancy in patients with primary immunodeficiency disorder [43]. The gene discussed is CD4; the disease is T-cell leukemia.