TTP diagnosed verse HUS?

My Bro diagnosed with Leukemia(AML & ALL) 5/09, received chemo, bone marrow trans. Will say he beat it to b point. Got GVH 9/09 in mouth. 10/01/2010 diagnosed w/TTP in which is common etc. Karmonos in MI. doing typical for TTP. Yet nothing working. Could he have a form of HUS? I know they can be misdiagnosed and understand for doctors to choose TTP based on statistics yet so far my Bro has had the rarest of everything. I know treatment is similar to the 2 yet not the same. Could he be saved with HUS treatment or would it kill him instantly etc. He is only 38, a fireman a brother, a husband and a father of 3? Please... those of you that know about TTP and HUS only respond. This is not a game... he's my brother that is dieing. My family needs good info since the doctors here are very closed minded. What are our options and whats your thoughts?