However, in recent years, it has been shown that mice with pure X monosomy survive and develop normally  and that human 45, X cells proliferate and differentiate into various cell types in vitro [7, 8].Moreover, with progress in genotype-phenotype research in humans and mice, it has become very clear that penetrance and expressivity of specific gene deletions is highly dependent on the individual genetic “background” and environmental factors.Tags: Homework First GradeHow To Write Good Business PlanCover Letters For Librarian PositionHoe To Write An EssayThesis For Music PaperPhd Thesis ReaderThomas Hobbes EssayEssays On To Kill A Mockingbird Themes
Haploinsufficiency for the pseudoautosomal gene termed SHOX is responsible for the short stature and skeletal anomalies characteristic of TS .
The genes related to cardiovascular and cognitive effects also map to the sex chromosome short arms [10, 11] but have not been identified.
This hypothetical scenario seems unlikely for several reasons.
Firstly, available research on human gametes and embryos indicates that aneuploidy and chromosomal fragmentation commonly occur during meiosis, related to errors of homologous recombination [3, 4].
This genomic technology represented a transition from classic cytogenetics through FISH to artificial chromosomes immobilized on arrays as shown here.
Figure 1: Xp deletion in a patient with BAV and aortic coarctation.Progress in cardiovascular MRI over the past decade has dramatically changed our view of the scope and criticality of congenital heart disease in TS.Cardiac MRI is far more effective than transthoracic echocardiography in detecting aortic valve abnormalities, descending aortic aneurysm, and partial anomalous pulmonary venous return; recent technical advances allow adequate imaging in girls as young as seven without breath holding or sedation.Some authors do not believe that complete X monosomy is compatible with survival and postulate the existence of a normal cell line that rescues the embryo during early gestation .This view suggests that most if not all surviving apparently 45, X girls arose via loss of the 2nd sex chromosome during early mitotic cell divisions in preimplantation embryos .Finally, important developments in the area of gynecological management of girls and young women with TS are reviewed, including prognostic factors that predict spontaneous puberty and potential fertility and recent practice guidelines aimed at reducing cardiovascular risk for oocyte donation pregnancies in TS.Clinical consensus defines Turner syndrome (TS) as a genetic disorder due to “complete or partial” X chromosome monosomy, with short stature the most constant feature, and variable expressivity of ovarian, cardiovascular, and renal defects .About 15% of patients in clinical series have mosaicism for 46, XX and/or 47, XXX cell lines in addition to 45, X cell line.This chromosomal constitution originates from sex chromosome loss during mitotic divisions occurring during early development.The past decade produced important advances in molecular genetic techniques potentially supplanting the traditional cytogenetic diagnosis of Turner syndrome (TS).Rapidly evolving genomic technology is used to screen 1st trimester pregnancies for sex chromosomal anomalies including TS, and genomic approaches are suggested for the postnatal diagnosis of TS.