XDH and acne: The results obtained by Sarici et al. [1] concerning the evaluation of parameters associated with oxidative stress, such as nitric oxide (NO), xanthine oxidase (XO), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT), in the venous blood of patients using spectrophotometrical methods indicate that oxidative damage of tissues is a significant etiological factor of acne.