I had never heard of Global Development Disorder until reading your post.
Having carried out a web search on it and read some information it seems that my brother would also be classed as having GDD. He is 54 years old and we were always told that he was mentally handicapped and that was it. I guess research and interest in people with learning disabilities has moved on since then. You may well have answered a question that I have been contemplating for a long time.
Our family have very recently asked his GP if they can tell us what his condition would be classed as now so we can contact other families and perhaps share information in the hope of improving his quality of life. He generally has a great quality of life but every little helps when you love someone. We know he has hypothyroidism (underactive thyroid) and this is listed as one of the causes at the following weblink:
This organisation describe themselves as follows:
We are Contact, the charity for families with disabled children
We support families with the best possible guidance and information. We bring families together to support each other. And we help families to campaign, volunteer and fundraise to improve life for themselves and others.
It looks really interesting. My brother is in full time residential care now but we feel the care home are not meeting his needs, so we are in the process of moving him. This is taking up quite a lot of time at the moment but when the move is finalised I shall definitely be spending some more time looking at their website in future.
I also came across the following website where you may find some useful information, even if you do not need legal advice.
Hopefully you’ll find some useful information on one of these websites.
Thank you for leading me to the answer I’ve been looking for.