<qa>  What is the major cause of non-relapse morbidity and mortality?For patients who survive allogeneic bone marrow transplants greater than 100 days, chronic GvHD is a major cause of non-relapse morbidity and mortality. Depending on the presence of known associated risk factors, chronic GvHD will occur in 20-50 of these transplant recipients, with mortality rates varying from 20 to 70. 