The X chromosome contains 155 million pairs of bases (pb) and over 1000 genes 16 while the Y chromosome has a length of 60 million pb and contains over 200 genes, from which only 48 are codifiers. 17 Inactivation of the X chromosome in women allows for an equilibrium in gene doses with respect to men; however, the so-called pseudoautosomic regions (PAR1 and PAR2) escape X chromosome inactivation and their genes are counterparts to those within PAR1 and PAR2 of the Y chromosome. Additionally, only in said regions is there a meiotic recombination among X and Y chromosomes.
The Turner’s syndrome phenotype can be explained by a haploinsufficiency of the genes which are normally expressed in both sexual chromosomes and which escape X inactivation
6 Mb of the short arm of sitios de citas chinos gratis X and Y human chromosomes. 18,19 It contains at least 24 genes, all of which escape X inactivation. 6 The PAR2 region is in the distal end of the long arm, and is much smaller since it only covers 320 kb 7 . It presents a lower recombination frequency and is composed of pseudogenes, for the most part. Four genes have been identified in this region ( HSPRY3 , VAMP7 , IL9R and CXYorf1 ) located in a telomeric center direction.
The SHOX gene (short-stature homebox) located in Xp (PAR1) belongs to the homebox gene family, which is a transcriptional regulator and key controller of multiple processes during embryonic development. Location of the SHOX expression during embryogenesis is correlated to many phenotypic features of Turner’s syndrome, since it intervenes in the development of the elbow and knee, its haploinsufficiency is associated with skeletal alterations such as cubitus valgum, genu valgum and Madelung deformity. Continue Reading Hence, a proper expression and function of these genes requires both alleles