Pericentric Inversion of X Chromosome in Male Fetus

[smartins]

So after further analysis and comparison there has been a shift of diagnosis from insertion to inversion, which I'm told is more favorable in terms of prognosis. The inversion in the male fetus has been determined as essentially the same as the inversion in the mother:

 

Mother karyotype = 46, X, inv(X)(p11.23q21.2)

 

Male fetus karyotype = 46, Y, inv(X)(p11.23q21)

 

Presently a chromosomal microarray is still pending on the mother and baby. Also a karyotype is being obtained on the mother's lone brother. We've been told that firstly because the pericentric inversion is apparently the same for the mother and baby that this is a good sign of normal phenotype. However the microarrays are needed for confirmation, particularly that there are no deletions or duplications of genetic information... balanced vs unbalanced inversion. We've also been told that if the mother's brother has the same pericentric inversion of the X chromosome this would be a favorable sign as well.

 

One confusing issue seems to be that because a female has 2 X chromosomes, if one is inverted, abnormal or unbalanced, then it could be inactivated with preferential usage of the uninverted and normal X chromosome. So assuming that is the case (which isn't actually known in this instance), how is it truly favorable if the male fetus' pericentric inversion of the X chromosome is identical to the mother's if the male obviously won't have the luxury of an alternative X chromosome for usage?

 

Beyond that, is it accurate to assume that if the pericentric inversion in the X chromosome in the male fetus is absent deletions or duplications (i.e. a balanced inversion), then the baby will be healthy/normal (i.e. absent consequences of the inversion other than possible reproductive issues)?

 

Any thoughts or comments would be appreciated as well.

 

Thank you.