Martha.  Your sons will both have your standard mutation as well as your husband’s obviously rarer more obscure mutation. It is true that some are more difficult to detect and if that is the case then a CVS test will not be able to give an accurate result as they will only be able to confirm one of the two mutations, which will mean if your mutation is not passed down, the child does not have CAH (but could be a carrier).  If your mutation is passed down, the child could either have CAH (as your husbands mutation could be present) or just be a carrier (if his defect isn’t passed down).