Basic InformationDefinition: a genetic disorder caused when abnormal cell division results in extra copy (full or partial) of genetic material from chromosome 21.
(click "definition" to visit the source) There are 3 types of Down syndrome and according to NDSS they are the following: Trisomy 21 (nondisjunction) accounts for 95% of cases, Translocation accounts for about 4%, and Mosaicism accounts for about 1%. Left side image from: Right side image from:
http://www.riverbendds.org/downkary.gif http://www.ds-health.com/images/chromo.gif The image to the left shows a set of chromosomes that belong to an individual with Down syndrome. For pairs 1-20 and 22, we see that there are 2 chromosomes above each, one from the mother and one from the father. When we get to pair 21, there is a third, or extra, chromosome (trisomy 21) which results in Down syndrome. The image to the right shows the contrast between chromosome pairs. This image represents an individual without Down syndrome.
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Misconceptions & Realities from the Global Down Syndrome Foundation
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Videos on the Basic Information
Each of these videos provides a brief explanation, as well as some of the characteristics and abilities of individuals with Down syndrome.
Parents Magazine
Explains a basic overview of Down syndrome and what to expect as parents. |
This video outlines the biological process of Down syndrome and compares the separation of the 21st chromosome to a single pair of 2 chromosomes.
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The Utah Down Syndrome Foundation provides a great explanation that can be used to explain the process that occurs as well as what to expect of your friends with Down syndrome to children.
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