Where to find support groups for people with growth disorders? (Young looking)?

Hello all. To make a long story short, my brother went through a decade of battling leukemia. (He is doing well, and in remission now). The most intense bit of radiation and chemotherapy was when he was around 11 years old, and this resulted in his body stopping its growth cycle. He is now 22, and looks/sounds like he is about 13. 

As you can imagine, this places a sort of damper on life for him, and affects friendships and relationships. What I’m trying to do is find a source of support for him. A group of similar individuals, who he can mingle and speak with, online or not. I want him to know people who have the same issue, but are thriving in life regardless. I don’t want him to feel alone in his struggle. Of course I support him and never treat him different; but he still needs people who understand and relate to his struggle fully. We have tried some research, but have not found much. So I’m hoping reaching out to the community will help, and that someone knows something.

Thank you all for your time and any help provided.