This issue has been addressed in the current study in which the systemic levels of various biomarkers of oxidative [8-hydroxy-2-deoxyguanosine (8-OH-dG) and cotinine] and inflammatory/immunosuppressive stress [CRP, IL-2, IL-4, IL-6, IL-10, Interferon-γ (IFN-γ), tumor necrosis factor- α (TNF-α)], as well as immunosuppression (inhibitory immune checkpoints and vitamin D) have been measured in an unusually large cohort (n=24) of patients with XP. This evidence concerns the gene IL4 and xeroderma pigmentosum.