What are the most important donor and recipient factors affecting the outcome of related and unrelated allogeneic transplantation?

Several recipient and donor risk factors affect outcome after transplantation with allogeneic hematopoietic stem cells. The most important recipient risk factors are patient age, comorbidity, performance status, cytomegalovirus (CMV) status, and disease considerations, such as diagnosis, stage, and cytogenetic risk. Prior chemotherapy regimens, patient race, and IL10 promoter polymorphism also appear to have some impact, but to a lesser extent. The most important donor factor is the level of HLA mismatch. Donor gender, relation, age, and KIR genotype also affect outcome. Donor CMV serology, parity, and race do not appear to affect outcome. These factors must all be considered in relation to one another when selecting whether to recommend patients for transplant.