Trisomy

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trisomy

[′trī‚sō·mē]
(cell and molecular biology)
The presence in triplicate of one of the chromosomes of the complement.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Trisomy

 

the presence of one or a few nonhomologous extra chromosomes in the chromosome set of a diploid organism. Organisms (or cells) in which one, two, or more chromosomes present themselves as three homologues are called simple trisomics, double trisomics, and so forth. Trisomy is caused by the failure of chromosomes to separate (nondisjunction) during cell division. Some specific severe disorders are the result of trisomy occurring in specific chromosomes.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.