Research has shown that by quantifying the expression levels of GMP, AMP, and IMP purine monophosphate in lymphocytes, red blood cells, and epidermal tissues of healthy individuals and psoriatic patients, the terminal metabolites of xanthine, hypoxanthine, and uric acid metabolism are accumulating, and the activity of ADA and PNP in the psoriasis patients skin is increasing (31). This evidence concerns the gene PNP and psoriasis.