I also read he had an autoimmune disease (I did not realize it until today) his whole life, which caused the kidney disease. He was never in good health I guess. Poor guy, but he always had such a good attitude, at least in public. I think he made the best of what he was dealt.
I read a long time ago that his adopted mother had somehow taken all his assets that he earned from the show Different Strokes and he had sued her to try and get the money back, but it was mostly gone..........