Monosomy X (Turner Syndrome) (2n = 44,XO)
Monosomy X (AKA Turner Syndrome) is a
karyotypic
condition caused by non-disjunction of X
chromosomes at Meiosis I
or II. It occurs in
about 1/2000 live
female births: a large proportion of monosomic X
fetuses are aborted spontaneously in the first trimester.
The second X is
completely absent in about 50%
of cases, partially deleted in about 30%,
and instances of tissue mosaicism (mixtures of XO and XX cells) are also
known.
The most obvious indications are very short stature (4'8" = 141cm in untreated adults, correctable with hormone replacement), webbing at the neck (not always present), characteristic facial features (compare the drawing and the girl in the first photo, but highly variable as in the remainder of the gallery), and a variety of secondary medical conditions. Girls with Turner Syndrome typically do not experience puberty without estrogen therapy, and there is a trade-off between height gain and early induction of sexual maturity. Ovaries are typically undeveloped and ova rare, but some cases of succesful reproduction are reported.
Contrary to state,emts in some textbooks, the range of intellectual development is normal, though there seem to be difficulties with specific skill sets, particularly math. The principal difficulty is acceptance by the peer group. Most women with Turner Syndrome lead typical lives, including normal family relationships. For further information, see [http://www.tss.org.uk] and [http://www.turner-syndrome-us.org].
The most obvious indications are very short stature (4'8" = 141cm in untreated adults, correctable with hormone replacement), webbing at the neck (not always present), characteristic facial features (compare the drawing and the girl in the first photo, but highly variable as in the remainder of the gallery), and a variety of secondary medical conditions. Girls with Turner Syndrome typically do not experience puberty without estrogen therapy, and there is a trade-off between height gain and early induction of sexual maturity. Ovaries are typically undeveloped and ova rare, but some cases of succesful reproduction are reported.
Contrary to state,emts in some textbooks, the range of intellectual development is normal, though there seem to be difficulties with specific skill sets, particularly math. The principal difficulty is acceptance by the peer group. Most women with Turner Syndrome lead typical lives, including normal family relationships. For further information, see [http://www.tss.org.uk] and [http://www.turner-syndrome-us.org].