From what I've heard the reverse is often true, CAH children are bright and quick to learn. I have certainly not experienced problems like this with my son, he has generally been 'normal' or 'above normal' with his development (he started walking at 11 months). The trouble with children is that they are all so different at a young age. A little girl (non CAH) at Christophers nursery isn't crawling or walking and she is 13 months. She gets frustrated by her not being able to join in with the others at nursery - perhaps this is the case with your grandaughter?