n. a mild form of the hereditary disorder ichthyosis, in which the skin develops slight dryness and forms branlike scales. It is common in the elderly. Xeroderma pigmentosum is a rare genetically determined disorder (see genodermatosis) in which there is an inherited defect in the DNA repair mechanism in the skin, which corrects ultraviolet radiation damage; this leads to multiple skin cancers. Affected individuals must avoid exposure to sunlight.
Subjects: Medicine and Health.