Found you! Thanks Bluebird for starting this thread and EJ for bumping it out of the twilight zone.
My DD is 4.9. She has extra material on chromosome 9. There are other factors that make her condition v. rare but when she was first diagnosed it was the information on duplication of chromo 9 that we were given as most closely matching her karyotype.
We were told when she was 2 weeks old that she had a chromo abnormality and it took another 5 weeks or so for us to be given the detail of the affected chromosome and then a few months before we saw the geneticist for the karyotype. The waiting and Googling I did in the interim were hideous.
My DH and I were tested straight away when DD was 2 weeks old. Looking back we didn't even hesitate because we didn't think it through, we just did it. In our case that was prob because we already had an older DC (NT) and were unlikely to have any more children although as I say I didn't consciously think it through at the time.
We were devastated by the diagnosis and I must admit that I grieved for the baby I thought I was having for a very long time. I remember DDs first birthday - it should have been a celebration of her life and all that she had achieved - but for me it was just a reminder of the day our lives changed forever and we stopped being a "typical" family.
I hope that's not disrespectful to anyone on this thread, I obviously don't mean it to be, it's just how I felt at the time.
Now, with DD 4.9 I can say that I'm definitely through the worst (about time!). DD makes us smile and laugh and is a happy soul who loves us and her DB with an innocence that is very humbling. She also causes us untold stress and worry
. I've had to train myself not to let thoughts wander too far into the future because I am prone to looking on the bleak side.
DD has achieved more that I dared hope she would back in the dark days of first diagnosis. We are hoping that she will start MS school next September with a 1:1 (we deferred her for a year).
I would agree with others that MN SN has been the most useful resource for us latterly with Unique being the most useful and supportive in the very early days - Beverly the CEO was very generous with her time answering my emails.
Anyway, sorry for the long ramble - just a bit excited that there's a thread specially for our DC 
Best wishes to you all. x