[Pigmentary lesions in patients with increased DNA damage due to defective DNA repair]

The occurrence of abnormally pigmented skin lesions is a common phenomenon and often associated with the influence of ultraviolet radiation (UV) and other sources of DNA damage. Pigmentary lesions induced by UV radiation and other sources of DNA damage occur in healthy individuals, but human diseases with defective DNA repair represent important models which allow the investigation of possible underlying molecular mechanisms leading to hypo- and hyperpigmentations. There are several hereditary diseases which are known to go along with genetic defects of DNA repair mechanisms comprising Xeroderma pigmentosum (XP), Cockayne syndrome (CS), Trichothiodystrophy (TTD), Werner syndrome (WS), Bloom syndrome (BS), Fanconi anemia (FA) and Ataxia telangiectasia (AT). These diseases share clinical characteristics including poikilodermatic skin changes such as hypo-and hyperpigmentation. Since UV radiation is the most common source of DNA damage which can cause pigmentary lesions both in healthy individuals and in patients with genetic deficiency in DNA repair, in the present article, we focus on pigmentary lesions in patients with XP as an example of a disease associated with genetic defects in DNA repair.