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Query: UMLS:C0022716 (Menkes)
 1,057 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lines of Blaschko represent a nonrandom developmental pattern of the skin fundamentally differing from the system of dermatomes. Many nevoid skin lesions display an arrangement following these lines. This is a review of case reports providing photographically documented evidence that the lines of Blaschko become manifest in the heterozygous state of various X-linked gene defects such as incontinentia pigmenti, focal dermal hypoplasia, X-linked dominant chondrodysplasia punctata, X-linked hypohidrotic ectodermal dysplasia, and Menkes syndrome. Hence, a causal relationship between lyonization and the lines of Blaschko seems quite obvious. Although it should be borne in mind that other genetic mechanisms such as somatic mutations or chimerism may give rise to the same linear pattern, the datable embryologic event of X-inactivation seems most suitable to explain the origin and nature of the lines of Blaschko. Apparently, in women affected with X-linked skin disorders the lines of Blaschko visualize the clonal proliferation of two functionally different populations of cells during early embryogenesis of the skin. The typical dorsal V-shape and the abdominal S-figure of these lines may result from an interference of the transversal coherent proliferation with the longitudinal growth and flexion of the embryo. In contrast to Blaschko's original assumption, it is now clear that these lines are independent from the metameric structure of the human body. Obviously, they represent a marker of the normal development of human skin. Therefore, a thorough study of the distribution pattern of X-linked skin disorders in women may give us a better insight into the early embryogeny of the human integument.
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PMID:Lyonization and the lines of Blaschko. 389 10

In X-linked inheritance, the difference between the terms dominant and recessive is blurred by the Lyon effect. In some X-linked recessive genodermatoses, the Lyon effect makes the detection of heterozygote females possible, either by clinical cromanifestations or by enzymatic demonstration of two functionally different populations of cells. The gene locus of X-linked recessive ichthyosis, however, escapes X-inactivation, but heterozygotes can be detected by enzyme analysis in this condition, too. X-linked dominant gene defects with manifestation in both sexes include keratosis follicularis spinulosa decalvans, and probably also the Bazex syndrome. The group of X-linked dominant gene defects with lethality in the male comprises incontinentia pigmenti, focal dermal hypoplasia, the oral-facial-digital syndrome and the CHILD syndrome. Prenatal diagnosis of severe X-linked conditions can be performed when the underlying defect of cell function is known (Fabry disease, Menkes syndrome). In other severe X-linked disorders, the possibility of prenatal determination of the sex may be considered (Wiskott-Aldrich syndrome, X-linked dominant chondrodysplasia punctata, oral-facial-digital syndrome).
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PMID:[X-chromosome-linked hereditary dermatoses]. 680 14