You’re right...if you have CAH, then your son would at least be a carrier and should have at least one mutation.  And if your daughter actually HAS CAH, then she should have two. 

But, I agree with Bonnie....the fact that they weren’t able to locate all the mutations doesn’t necessarily mean anything. Usually, the gene testing labs test first for the 10 most common mutations, though more than 50 (I believe) have been identified.  So it could jsut be that your kids carry mutations other than what they tested for.  Or perhaps they carry a mutation which has not even been identified.

Exon 7 refers to a specific location on the 21-hydroxylase gene.  Of the 10 most common mutations, two have been identified on Exon 7.  The more common one (called V281L) is usually associated with late onset CAH, while the less common one is associated with salt-wasting CAH.  From what you’ve said on the mb previously, it sounds like your daughter probably has the V281L defect?