These changes result from defective DNA repair of damage done by ultraviolet radiation. When exposed to sunlight the UV radiation induces thymine dimmers and other damage in the DNA of human cells.
Normal individual have several mechanisms for repairing damaged DNA. These mechanisms are absent to various degrees in patients affected with Xeroderma pigmentosum.
Xeroderma pigmentosum was first named by Hebra and Kaposi in 1874 and the association of Xeroderma pigmentosum with neurological dysfunction by de Sanctis and Cacchione in 1932.
Clinical hallmarks of Xeroderma pigmentosum
*Severe photosensitivity
*Poikiloderma
*Dryness (xerosis)
*Premature skin aging
*Malignant tumors (squamos cell cancers, basal cell cancers and melanoma), most often on face, head and neck
Xeroderma pigmentosum is one of the few diseases that can cause poikiloderma at an early age. Poikiloderma is characterized by erythema, hyper and hypopigmentation as well as scaring and telangiectasias.
Xeroderma pigmentosum occurs in all races and affects both sexes equally.
Xeroderma pigmentosum
