I’m not sure what heterozygous CAH would be, or if it is just another name for CAH, but the consensus of parents on this board is that CAH kids seems to do a little better in school than average. Of course you have to keep in mind that this is from parents. I have 2 CAH kids, one 8 and one 4. The 8 year-old is doing grade level in every subject except math, where he’s about 3 grades ahead.  The 4 year-old is doing JumpStart Kindergarten on her computer, and seems to understand it well enough.