any of various skin diseases characterised by dry hard scaly skin, especially ichthyosis.
xp is a fatal variant of xeroderma pigmentosum for which there is no known cure. in extreme cases, even a glint of sunlight can cause malignant skin cancers. dorey and yolanda nez of new mexico lost their son and daughter to xp. both children also suffered from neurological degeneration, which can accompany the disease. everydayhealth.com
xeroderma pigmentosum is a disorder that appears to result from an inherited hypersensitivity to the cancer-causing (carcinogenic) effects of ultraviolet light. sunlight causes dna damage that is normally repaired. individuals with xeroderma pigmentosum have defective inability to repair the dna after uv damage. affected individuals are hundreds of times more vulnerable to developing skin cancer than other people. their extreme skin photosensitivity predisposes them to pronounced skin damage and scarring and also to the early onset of skin cancer (basal cell and squamous cell carcinomas and malignant melanoma). medicinenet.com
rarely, mutations in the ercc2 gene can cause features of both xeroderma pigmentosum and trichothiodystrophy in the same individual. this condition is known as xeroderma pigmentosum/trichothiodystrophy (xp/ttd) complex. ercc2 gene mutations have also been identified in a few individuals with signs and symptoms of both xeroderma pigmentosum and another condition related to defective dna repair called cockayne syndrome. this combination of features is known as xeroderma pigmentosum/cockayne syndrome (xp/cs) complex. medlineplus.gov
the case authors note that scc usually affects the exposed part of the eyeball in sun-damaged conjunctiva at the limbus. ultraviolet b radiation is the primary risk factor, with other risk factors including immunosuppression (hiv/aids), human papilloma virus, and allergic conjunctivitis, as well as smoking, petroleum product exposure, and genetic predisposition in conditions such as xeroderma pigmentosa. medpagetoday.com
normal skin owes its soft, pliable texture to its water content. to help protect against water loss, the outer layer of skin contains oil, which slows evaporation and holds moisture in the deeper layers of skin. if the oil is depleted, the skin becomes dry. dry skin, unless it is an inherited disorder or is caused by another condition, is called xeroderma. merckmanuals.com