Turner syndrome: an updateand review for the primary pediatrician. Doswell BH, Visootsak J, Brady AN, Graham JM Jr. ![]() Care of girls and women with Turnersyndrome: a guideline of the Turner Syndrome Study Group. New issues in the diagnosis and management of Turner syndrome. Rarely, Turner syndrome caused by a partial deletion of the X chromosome can be passed from one generation to the next. Other sex chromosome abnormalities are also possible in females with X chromosome mosaicism. As a result, some of an affected person's cells have the usual two sex chromosomes, and other cells have only one copy of the X chromosome. In an affected individual, it occurs as a random event during cell division in early fetal development. Mosaic Turner syndrome is also not inherited. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have a single X chromosome in each cell and will be missing the other sex chromosome. For example, an egg or sperm cell may lose a sex chromosome as a result of nondisjunction. ![]() An error in cell division called nondisjunction can result in reproductive cells with an abnormal number of chromosomes. When this condition results from monosomy X, the chromosomal abnormality occurs as a random event during the formation of reproductive cells (eggs and sperm) in the affected person's parent. Most cases of Turner syndrome are not inherited. The loss of one copy of this gene likely causes short stature and skeletal abnormalities in women with Turner syndrome. They have, however, identified one gene called SHOX that is important for bone development and growth. Researchers have not determined which genes on the X chromosome are associated with most of the features of Turner syndrome. Women with Turner syndrome caused by X chromosome mosaicism are said to have mosaic Turner syndrome. Some women with Turner syndrome have a chromosomal change in only some of their cells, which is known as mosaicism. Turner syndrome can also occur if one of the sex chromosomes is partially missing or rearranged rather than completely absent. The missing genetic material affects development before and after birth.Ībout half of individuals with Turner syndrome have monosomy X, which means each cell in the individual's body has only one copy of the X chromosome instead of the usual two sex chromosomes. Turner syndrome results when one normal X chromosome is present in a female's cells and the other sex chromosome is missing or structurally altered. People typically have two sex chromosomes in each cell: females have two X chromosomes, while males have one X chromosome and one Y chromosome. Turner syndrome is related to the X chromosome, which is one of the two sex chromosomes. Developmental delays, nonverbal learning disabilities, and behavioral problems are possible, although these characteristics vary among affected individuals. ![]() Most girls and women with Turner syndrome have normal intelligence. Complications associated with these heart defects can be life-threatening. One third to one half of individuals with Turner syndrome are born with a heart defect, such as a narrowing of the large artery leaving the heart (coarctation of the aorta) or abnormalities of the valve that connects the aorta with the heart (the aortic valve). A small percentage of females with Turner syndrome retain normal ovarian function through young adulthood.Ībout 30 percent of females with Turner syndrome have extra folds of skin on the neck (webbed neck), a low hairline at the back of the neck, puffiness or swelling (lymphedema) of the hands and feet, skeletal abnormalities, or kidney problems. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive (infertile). The ovaries develop normally at first, but egg cells (oocytes) usually die prematurely and most ovarian tissue degenerates before birth. An early loss of ovarian function (ovarian hypofunction or premature ovarian failure) is also very common. The most common feature of Turner syndrome is short stature, which becomes evident by about age 5. Turner syndrome is a chromosomal condition that affects development in females.
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