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(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 It might be outdated or ideologically biased.



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.
References in periodicals archive ?
Klinefelter Syndrome and Trisomy X are known as sex chromosome aneuploidy, or variations in the typical number of chromosomes.
We used the following criteria to identify trisomy 21 fetuses:
Receiver operating characteristic (ROC) analysis was performed to determine the specificity and sensitivity of AMELX and AMELY genes as an indicator of male embryos and for TTC3 and RPL17 to analyze Trisomy 21 and Trisomy 18.
Wong, and V Dezerega, "First-trimester sonographic findings in trisomy 18: a review of 53 cases," Prenatal Diagnosis, vol.
The study sample had either an intermediate or a high background risk for trisomy 21, largely based on maternal age.
* We describe a 2.5-year-old male case of mosaic trisomy 9 with a moderate developmental delay.
When prenatal or neonatal diagnosis of trisomy 18 is made, the counselling of the family should be realistic but not desolate.
Trisomy 21 is a common birth defect and can be diagnosed easily on the basis of clinical features.
Although the detection rate of cfDNA for trisomy 21 is higher than that of traditional screening, the detection rate of traditional screening is also quite high at lower cost.
All commercially available cfDNA tests have high sensitivity and specificity for trisomy 21, 18, and 13.
In a prospective, international study published earlier this year that compared cfDNA testing to standard screening for trisomy 21, cfDNA testing identified trisomy 21 in all 38 women with the abnormality, compared to 30 ]of 38 with standard screening.
The book covers the musculoskeletal system of a 28-week human trisomy 18 cyclopia fetus; the comparative anatomy of muscular anomalies in trisomies 13,18, and 21; cyclopia, trisomic anomalies, and order-versus-chaos in development and evolution; digits and muscles: topology-directed muscle attachment; and evolutionary mechanisms and mouse models for Down syndrome.