Larina V.N. et al. in their scientific investigation in 2016, pointed to the role of chronic tissue hypoxia in cardiovascular diseases and in the development of endothelial dysfunction, which in turn leads to an increment in the activity of xanthine oxidase enzyme and the accumulation of uric acid as the final product of purine metabolism, in the plasma (6). The gene discussed is XDH; the disease is endothelial dysfunction.