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Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human somatic cell having 45 or 47 chromosomes instead of the usual 46. [1] [2] It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell. [1]
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]
[citation needed] An example of trisomy in humans is Down syndrome, which is a developmental disorder caused by an extra copy of chromosome 21; the disorder is therefore also called "trisomy 21". [7] An example of monosomy in humans is Turner syndrome, where the individual is born with only one sex chromosome, an X. [8]
Two examples of natural autopolyploids are the piggyback plant, Tolmiea menzisii [19] and the white sturgeon, Acipenser transmontanum. [20] Most instances of autopolyploidy result from the fusion of unreduced (2 n ) gametes, which results in either triploid ( n + 2 n = 3 n ) or tetraploid (2 n + 2 n = 4 n ) offspring. [ 21 ]
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child. There are over 6,000 known genetic disorders in humans.
Karyotype of a human with Trisomy 21 (Down syndrome). Trisomies can occur with any chromosome, but often result in miscarriage rather than live birth.For example, Trisomy 16 is most common in human pregnancies, occurring in more than 1%, but the only surviving embryos are those having some normal cells in addition to the trisomic cells (mosaic trisomy 16). [3]
What they look like: Chiggers, a type of small mite, typically leave clusters of bites that are often very itchy. In many cases, chigger bites appear as small, red and itchy bumps. Sometimes, they ...
XXXY syndrome is a genetic condition characterized by a sex chromosome aneuploidy, where individuals have two extra X chromosomes. [3] People in most cases have two sex chromosomes: an X and a Y or two X chromosomes. The presence of one Y chromosome with a functioning SRY gene causes the expression of genes that determine maleness. Because of ...