Down syndrome is also known as "Trisomy 21" - a reference to the fact that someone with Down syndrome has 3 pairs of chromosomes 21.
A genetic disorder caused by the presence of all or part of a third copy of chromosome 21.
Down syndrome is a chromosomal disorder. It is caused by having 1 extra chromosome (chromosome 21).
Trisomy means having three copies of a chromosomes. Turner's syndrome is NOT an example of trisomy. Someone with Turner's syndrome has only one X chromosome. Down's syndrome IS an example of trisomy. Someone with Down's syndrome has 3 copies of chromosome 21. Klinefelter's syndrome is a tricky one. On one hand, it would be considered trisomy because they have 3 sex chromosomes. However, they are not all the SAME sex chromosomes. Someone with Klinefelter's has 2 X chromosomes and one Y chromosome.
Most cases of Down syndrome result from trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies. The extra genetic material disrupts the normal course of development, causing the characteristic features of Down syndrome.Hope this helps.
Four types of chromosomal mutations are Down syndrome (which is a mutation in which there are three copies of chromosome 21), Kinefelter Syndrome (which is a mutation in which a male has an extra X-chromosome), Turner Syndrome (which is a mutation in which a female is missing an X-chromosome), and Patau Syndrome (which is a mutation in which there are three copies of chromosome 13).
chromosome 21
The presence of three copies of a chromosome is known as a trisomy. An example would be Trisomy 21, also known as Down Syndrome.
Down syndrome results when cells receive three copies of chromosome 21.
The condition in which an individual has three copies of a chromosome is called trisomy. It can result in genetic disorders such as Down syndrome, which is caused by an extra copy of chromosome 21.
chromosome 21
Four types of chromosomal mutations are Down syndrome (which is a mutation in which there are three copies of chromosome 21), Kinefelter Syndrome (which is a mutation in which a male has an extra X-chromosome), Turner Syndrome (which is a mutation in which a female is missing an X-chromosome), and Patau Syndrome (which is a mutation in which there are three copies of chromosome 13).
Chromosome 21 is tripled in Down syndrome.