Trisomy 21: How an extra little chromosome throws entire genome off balance
A new study sheds light on how the extra chromosome 21 upsets the equilibrium of the entire genome, causing a wide variety of pathologies. Occurring in about one per eight hundred births, Down syndrome -- or trisomy 21 -- is the most frequent genetic cause of intellectual disability. It results from a chromosomal abnormality where cells of affected individuals contain a third copy of chromosome 21 (1% of the human genome).
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