The way I think of any children with special needs is that we never know what is round the corner. My youngest of 3 has special needs (genetic condition, called Sotos syndrome - causes overgrowth and delayed development). Not diagnosed until she was nearly 3 (she is now nearly 6) and, yes, she has struggled in the past, it has been hard on her elder siblings (now nearly 15 and nearly 11) but we would not be without her, and nor would they.
Okay, they were older when she was born (daughter was nearly 9 and son nearly 5) but they have still had to put up with the numerous hospital appointments in trying to find out what was wrong.
With any genetic condition, you can read as much as you like to be informed but no-one can predict the long term outcome.
Some children with Sotos syndrome never catch up and are still in nappies at 21! When my DD was first diagnosed, I read everything I could because I, incorrectly, thought fore-warned was fore-armed (and I spent many hours/days in tears thinking about what her future may be) but my DD, although still slightly behind, goes to mainstream school, is dry and clean both day and night, is sociable (children with Sotos are normally not sociable) and is an absolute delight.
Me and my husband split when she was 11 weeks old (not due to her).
Because she is still only 5 we do not know what the long term future holds for her, but as long as she can be the best that she can (and the amount of help and support that she receives from her family, friends, outside influences - speech and learning therapy, occupational therapy, physiotherapy - is unsurmountable), whatever is thrown at her and us (as her family) we will take in our stride.
She may (or may not) grow up to lead an independent life but we will cross that bridge when we come to it.
Unfortunately, Sotos syndrome (a genetic condition like Down Syndrome) is not detectable before birth but there are many conditions, a lot worse than Sotos Syndrome or Downs Syndrome and, even if Sotos was detectable before birth, I would still be where I am right now - a single mother to 3 children (although my biggest issue is that I have just turned 40!!!) - that is worse than having any children with special needs.
My eldest daughter (nearly 15) was 9 when Sasha was born and was nearly 12 when Sasha was diagnosed. Obviously, on first hearing the diagnosis and reading all the stories about these children, I spent many days/hours upset at what the future might hold for me and my family but my eldest daughter said she was quite glad that Sasha had Sotos as it made her who and what she was (tantrums, special needs, delayed development et al) and the diagnosis did not change who Sasha was. As long as Sasha can be the best she can (whatever that may be) then we should be grateful for the little ray of sunshine that she brings into our life and my eldest said she would not change her for the world.
My eldest said that the day before the diagnosis to the day I got the diagnosis that Sasha was still the person she was the day before I got the diagnosis - the only difference to Sasha was that she now had a "name" for her difference.
She told me I should not lose sight of Sasha because she was still the same person, diagnosis or not.
Sorry if I have rambled but I never thought I would have a child with special needs but we all deal with what we are put up against and she is the most adorable little girl and she just makes me smile.
I never think that she will be a "burden" to her older brother or sister because, from a young age, they have known Sasha for who and what she is (good and bad).