1. trisomy

noun. chrosomal abnormality in which there is one more than the normal number of chromosomes in a cell.


  • mongolism
  • chrosomal abnormality
  • Down's syndrome
  • Down syndrome
  • mongolianism
  • chromosomal aberration
  • chromosonal disorder
  • trisomy 21


  • -y (English)
  • -y (Middle English (1100-1500))
  • trisome (English)
  • -some (English)

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2. 21

adjective. being one more than twenty.


  • twenty-one
  • xxi


  • unimportant
  • fifty-fifth
  • forty-third

3. 21

noun. the cardinal number that is the sum of twenty and one.


  • XXI
  • twenty-one


  • eleventh
  • 48th
  • hundred-and-fortieth

Sentences with trisomy-21

1. Noun Phrase
One of the most well-known chromosome disorder of this type is Down Syndrome, or trisomy 21, which results from the presence of a third copy of the number 21 chromosome.

2. Noun Phrase
The incidence of trisomy 21 is about 1 in 800 births, and it is the most common genetic cause of mental retardation.

3. Noun Phrase
For instance, *trisomy 21* (Down syndrome) is caused by an extra copy of chromosome 21 in the egg or sperm that results in the fertilized egg receiving three copies of chromosome 21.

4. Noun Phrase
In a condition called trisomy 21, usually, three copies of chromosome 21 are produced in each cell, resulting in what is commonly known as Down syndrome.