M.G.
Ok, the one thing I know is that children with a hole are generally smaller not taller then their peers, it has something to do with the arteries NOT getting blood to where it needs to be for growth. I would look on the net for info. and keep a small spiral bound note book with you now at all times, just for little man's health notes. This way you can jot answers, questions, notes, tests, time line of care (you are his manager) ... Remember, Dr.s are busy so they are NOT going to go through his whole chart before your appointment so you having this info. at your finger tips - especially a time line and test info. will make the most of an apt. I learned this with my daughter and ask - do you have any literature you can give me - ask everyone who cares for your son. I started doing this when our daughter went to UNC, I was picking their brain period and I took the time to write everything down, a lot of health care people gave me their business card in case I had questions later.
My husband is an O.R. Nurse and although he may not know as much as a Dr. he always tells me "don't leave until all your questions are answered". Another thought, your insurance may offer an "ask a nurse program", use it, they can be helpful. I personally don't like united way, but they may help you.
Oh and I have a folder too for copies of tests, notes, and time lines ready to pull out and give to a dr. They appreciate you being prepared. Good luck, hope this helped. M.