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Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. [3] It is usually associated with developmental delays, mild to moderate intellectual disability, and characteristic physical features. [1] [12] There are three types of Down syndrome, the ...
Turner syndrome. Turner syndrome ( TS ), also known as 45,X, or 45,X0, is a genetic disorder in which a person's cells have only one X chromosome or are partially missing an X chromosome ( sex chromosome monosomy ). [2] [6] Most people have two sex chromosomes (XX or XY). The chromosomal abnormality is often present in just some cells, in which ...
Chromosome 10 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. People normally have two copies of this chromosome. Chromosome 10 spans about 134 million base pairs (the building material of DNA ) and represents between 4 and 4.5 percent of the total DNA in cells .
XXYY syndrome is a sex chromosome anomaly in which males have 2 extra chromosomes, one X and one Y chromosome. Human cells usually contain two sex chromosomes, one from the mother and one from the father. Usually, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). The appearance of at least one Y chromosome with ...
Frequency. ~1 in 1,000 males [1] XYY syndrome, also known as Jacobs syndrome, is an aneuploid genetic condition in which a male has an extra Y chromosome. [1] There are usually few symptoms. [2] These may include being taller than average and an increased risk of learning disabilities.
Genetics of Down syndrome. Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole ( trisomy 21) or part (such as due to translocations ). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy ...
The term idiot savant (French for "learned idiot") was first used to describe the condition in 1887 by John Langdon Down, who is known for his description of Down syndrome. Down described approximately ten cases of youth he had known with unusual mental powers, like "verbal adhesion" (eg. memorizing books read once), photographic memory for ...
Down syndrome research. Research of Down syndrome-related genes is based on studying the genes located on chromosome 21. In general, this leads to an overexpression of the genes. [1] [2] Understanding the genes involved may help to target medical treatment to individuals with Down syndrome. It is estimated that chromosome 21 contains 200 to 250 ...