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Turner syndrome (TS), commonly known as 45,X, or 45,XO, [note 1] is a chromosomal disorder in which cells have only one X chromosome or are partially missing an X chromosome (sex chromosome monosomy) leading to the complete or partial deletion of the pseudoautosomal regions (PAR1, PAR2) in the affected X chromosome.
The purple cell has 2 Y-chromosomes and 1 X-chromosome caused by the ovum fusing with a sperm cell with two Y-chromosomes, which was due to division problems in MII of the male. 47,XYY is not inherited; it usually occurs as a random event during the formation of sperm cells.
This XXY chromosome arrangement is one of the most common genetic variations from the XY karyotype, occurring in approximately one in 500 live male births. [4] [13] [36] In mammals with more than one X chromosome, the genes on all but one X chromosome are not expressed; this is known as X inactivation. This happens in XXY males, as well as ...
Typical XX females undergo X inactivation during which one copy of the X chromosome is silenced. It is thought that X inactivation in XX males may account for the genital ambiguities and incomplete masculinization seen in SRY-positive XX males. [22] [21] The X chromosome with the SRY gene is preferentially chosen to be the active X chromosome ...
In 45,X/46,XY, most or all of the Y chromosome is lost in one of the newly created cells. All the cells then made from this cell will lack the Y chromosome. All the cells created from the cells that have not lost the Y chromosome will be XY. [11] The 46,XY cells will continue to multiply at the same time as the 45,X cells multiply.
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 a properly functioning SRY gene makes a male. Therefore, humans with XXYY are genotypically male. Males with ...
For example, the X chromosomes of humans and chimpanzees are about 98 percent identical in makeup. On the other hand, only about one-third of the Y chromosomes of the two species matched.
Turner syndrome (Ullrich-Turner syndrome and gonadal dysgenesis) – a condition that describes a female born with only one X chromosome or with an abnormal X chromosome, making her karotype 45,X0. It occurs in 1 in 2,000 to 5,000 females. [ 61 ]