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What is trisomy 21?
Quick Answer
Trisomy 21 is a genetic condition caused by an extra copy of chromosome 21. It is the most common chromosomal cause of Down syndrome.
The Full Story
Trisomy 21 means a person has three copies of chromosome 21 instead of the usual two. This extra genetic material changes development and can affect intellectual development, muscle tone, heart structure and other body systems. Down syndrome is the clinical condition associated with trisomy 21, though rare translocation or mosaic forms also exist. It was first accurately linked to chromosome 21 in 1959.
Key Facts
1.People usually have 46 chromosomes, but trisomy 21 adds one extra
2.It is the most common chromosomal cause of Down syndrome
3.The chromosomal cause was identified in 1959
YouTube Angle
Suggested video title for this topic:
"The chromosome change behind Down syndrome"
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