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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 ...
Trisomy 22 is a chromosomal disorder in which three copies of chromosome 22 are present rather than two. It is a frequent cause of spontaneous abortion during the first trimester of pregnancy. Progression to the second trimester and live birth are rare. This disorder is found in individuals with an extra copy or a variation of chromosome 22 in ...
Cri du chat syndrome. Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. [1] Its name is a French term ("cat-cry" or "call of the cat") referring to the characteristic cat-like cry of affected children (sound sample [1] ). [2] It was first described by Jérôme Lejeune in 1963. [3]
Trisomy 21 – Down syndrome, an example of a polysomy at chromosome 21. Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. [1]
Trisomy X, also known as triple X syndrome and characterized by the karyotype [note 1] 47,XXX, is a chromosome disorder in which a female has an extra copy of the X chromosome. It is relatively common and occurs in 1 in 1,000 females, but is rarely diagnosed; fewer than 10% of those with the condition know they have it.
Ring chromosome 20 syndrome. Ring chromosome 20, ring-shaped chromosome 20 or r (20) syndrome is a rare human chromosome abnormality where the two arms of chromosome 20 fuse to form a ring chromosome. The syndrome is associated with epileptic seizures, behaviour disorders and intellectual disability. [1]
Individuals with ring 18 have one of their two copies of chromosome 18 that has formed the shape of a ring. The ring is formed when the caps on both the long arm (q) and the short arm (p) of one copy of chromosome 18 are lost and the new ends re-join to form the ring. Because the ring involves deletions of both the long arm (18q-) and the short ...
in human male karyogram. Chromosome 10 is one of the 23 pairs of chromosomes in humans. 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 .