The presence of three copies of a chromosome is known as a trisomy. An example would be Trisomy 21, also known as Down Syndrome.
trisonomy
Trisomey-21
A trisomy is a condition in which a person has three copies of a chromosome instead of the usual two copies. Trisomy 9 refers to three copies of chromosome 9. A person can have full trisomy 9 (three copies in every cell) or mosaic trisomy 9 (three copies in some cells but not all).
People with Down syndrome, also called mongoloidism have 47 chromosomes. Having 65 chromosomes would be lethal, as normally having 47 chromosomes is lethal. Down syndrome is also known as trisomy 21, because instead of two copies of chromosome 21, a person with Down syndrome has three copies, which accounts for the 47th chromosome.
Patau syndrome is the result of trisomy 13. Trisomy 13 is usually caused by having an extra chromosome in every cell in the body. Every cell in the human body should contain two chromosomes, one from each parent, however every one in sixteen thousand newborn has three chromosomes. The result of a third chromosome can mean physical disabilities. Most children die within a few days after birth. The disease is not inherited.
trisomy!
Triploid.
trisonomy
chromosome 21
In one kind of abnormal chromosome inheritance called Down syndrome, a child has three copies of Chromosome 21!
A trisomy is a condition in which a person has three copies of a chromosome instead of the usual two copies. A person can have full trisomy (three copies in every cell) or mosaic trisomy (three copies in some cells but not all).
Down syndrome results when cells receive three copies of 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).
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).
Trisomey-21
Edwards' syndrome is caused by an extra (third) copy of chromosome 18. The extra chromosome is lethal for most babies born with this condition. It causes major physical abnormalities and severe mental retardation. Very few children afflicted with this syndrome survive beyond the first year.
A trisomy is a condition in which a person has three copies of a chromosome instead of the usual two copies. Trisomy 9 refers to three copies of chromosome 9. A person can have full trisomy 9 (three copies in every cell) or mosaic trisomy 9 (three copies in some cells but not all).