n. any genetically determined skin disorder, such as *ichthyosis, *neurofibromatosis, or *xeroderma pigmentosum.
n. a genetically determined skin disorder (see genodermatosis) in which there is abnormal scaling of the skin (the scaly condition of the skin is reflected in the name of this disorder, which is derived from the Greek word for fish). Ichthyosis may be caused by a variety of genetic defects in skin shedding; the pattern of scaling varies according to the underlying defect. The commonest form, ichthyosis vulgaris, is inherited as an autosomal *dominant and occurs in 1 in 300 of the population. Lamellar ichthyosis is a very rare condition in which the skin, particularly on the palms and soles, is thickened and lizard-like. Treatment of ichthyosis is mainly by the regular use of emollients. See also xeroderma.... ichthyosis
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.... xeroderma
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