Hi there Amir and 2BPilot.
My son Evan was diagnosed with sAA, treated unsuccessfully with horse ATG and went on to have a completely successful unrelated, imperfectly matched BMT all within a year of his diagnosis. He was treated at McMaster Children's Hospital in Hamilton and Toronto's SickKids. This was when he was 10, 7 years ago. His Caringbridge link is below in my signature and he is profiled
HERE at Marrowforums, where his entire journey is summarized.
Best wishes to your cousin, I think it's fantastic that you're sourcing out info for he and his family.