Down syndrome - Definition

January 2017


Definition


Down syndrome, or trisomy 21, is a genetic disease associated with the 21 chromosome added onto the DNA. Chromosomes work in pairs, hence the name "trisomy" given to indicate the existence of a third chromosome. Down syndrome manifests with essentially facial malformations, with recognizable features such as a round, flat face, and slight folds across the inner corner of the eye. People with Down syndrome usually have small but wide hands and feet, and more or less severely decelerated psychomotor development. Down syndrome can be screened for during pregnancy if suspected on ultrasonography (called Nuchal translucency screening), or if the pregnant woman is of an advanced age, as pregnancy in older women are associated with a larger number of children born with Down syndrome. Affected individuals typically have slightly shorter lives that the normal population, and the principal risk facing them is of cardiac conditions.

Related

Original article published by . Translated by Jeff. Latest update on November 12, 2013 at 05:18 AM by Jeff.
This document, titled "Down syndrome - Definition," is available under the Creative Commons license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM Health (health.ccm.net).