My dog has cushings disease. (and I'm not making fun of the situation, he seriously does)
I don't know much about it for humans. But it's definitely treatable. I think it just depends on the individual who has it--how bad it is. Shouldn't be too much to worry about though. My uncle knew some kid who had it. Sometimes surgeries are needed; sometimes medications. Still, it shouldn't cause any dramatic problems. As the rest have said, talk to a doc. And best of luck to you and your bro.