Thus, it seems that X monosomy need not always be lethal, and the survival and relatively healthy development of some 45, X girls are more likely related to variation in autosomal genes and/or maternal effects that compensate for the sex chromosome haploinsufficiency, as opposed to cryptic rescue cell lines.The term “partial X monosomy” includes two distinct chromosomal etiologies for TS.Haploinsufficiency for the pseudoautosomal gene termed SHOX is responsible for the short stature and skeletal anomalies characteristic of TS .
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].
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.
The phrase “complete or partial” is used to include several chromosomal etiologies leading to the syndrome.
The most common is pure X monosomy (45, X—formerly designated 45X0).
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.
This type of mosaicism does not ameliorate the phenotype since all cells have monosomy for the X chromosome short arm (Xp).
The major phenotypic features of TS such as short stature, congenital cardiovascular defects, and neurocognitive differences are linked to deletion of X or Y chromosome short arms [9–11].