Lyonization

The inactivation of an X chromosome. One of the two X chromosomes in every cell in a female is randomly inactivated early in embryonic development. Named after geneticist Mary Lyon.
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The normal phenomenon that wherever there are two or more haploid sets of X-linked genes in each cell all but one of the genes are inactivated apparently at random and have no phenotypic expression. L. is usual but not invariable for all loci. Its randomness explains the more variable espressivity of X-linked traits in women than in men. L. occurs in men with the Klinefelter (XXY) karyotype. SEE ALSO: gene dosage compensation. SYN: Lyon hypothesis, X-inactivation. [M. Lyon]

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ly·on·iza·tion (li″on-ĭ-zaґshən) [M.F. Lyon] the process by which or condition in which all X chromosomes of the somatic cells in excess of one are inactivated on a random basis. Called also X-chromosome inactivation. See also Lyon hypothesis, under hypothesis.

Medical dictionary. 2011.

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  • lyonization — lyonization. = X inactivation (см.). (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • lyonization — lyonization. См. инактивация Х хромосомы. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • lyonization — …   Useful english dictionary

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  • X-inactivation — The Barr body is indicated by the arrow, it identifies the inactive X (Xi).] macroH2A1 staining. Arrow points to sex chromatin in DAPI stained cell nucleus, and to the corresponding sex chromatin site in the histone macroH2A1 staining.] X… …   Wikipedia

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