Alfred,
Your brother deserves a lot better. I'm sorry to hear about the severity of his GVHD. Is he getting all of his nutrition by IV? What did his doctor tell you about the goals of the ATG treatments? How are your brother's blood counts? Despite the GVHD, is he considered cured of the MDS? That would be a silver lining in this storm cloud.
I know how awful GVHD can be. My wife had GVHD of the digestive system after her transplant for MDS, affecting her mouth, tongue, throat, esophagus, and stomach. Even after talking to the doctors, we never understood what mechanism lets GVHD dissipate over time, but eventually the primary symptoms lessened. Although my wife's digestive system is still sensitive, it's now a background condition and the constant discomfort is gone.
Did you have the talk you mentioned with your brother's doctor? What did you learn? Have you considered getting a second opinion about the best approach at this point? Have you talked to the wonderful people at the
Aplastic Anemia & Myelodysplasia Association of Canada (AAMAC)?
The first year is the hardest so you may have to take it one day at a time until things get better. I really hope your brother can get past these dire straits soon. To answer your question, he did nothing to deserve this condition and neither did the rest of us. Nobody deserves MDS or the effects of its treatment. You're a hero both for donating stem cells to save your brother's life and for looking for information to help him now.