X Chromosome Inactivation

[habana999]

i guess i have to be quicker writing my post as I seemed to have been logged out for inactivity!!!

 

I have a question that has been puzzling me since studying biology of the cell and basic genetics

 

Why is it that the Barr body only forms in the XX phenotype and not the XY phenotype, i.e. how does one X chromosome know it has another beside it?

 

Interestingly while trying to find this out I came across two studies on familial skewed X inactivation stating that where a high inactivation of either the male or female X chromosome occured (it only stated female X chromosome inactivation but I am trying not to be biased here) there was a high incidence of spontaneous abortion:

 

'Sangha et al. (1999)' account for a significant proportion (i.e., as much as 18%) of couples with recurrent spontaneous abortion. Lanasa et al. (1999)reported similar results for women who experienced 2 or more spontaneous abortions.

 

Natures way of preventing hereditary genetic disease?

 

Comments appreciated

 

 

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=300087