For a blood cancer sufferer who has remained unresponsive to all other treatment options there is usually only one last glimmer of hope. This last resort involves treatment with blood stem cells, called haemopoietic cells, from an unrelated, living donor.
An allele is an alternative form of a gene. For example, one member of a pair that is located at a specific position on a specific chromosome. To determine if a donor is a match, Doctors look for matches of the human leukocyte antigen (HLA) type of five key alleles that occur in the blood stream. The goal is to achieve a 10/10 match to reduce the complications associated with transplants, such as the occurrence of acute Graft versus Host Disease. However, due to a host of complex reasons that are not yet fully understood, even a 10/10 match does not guarantee a successful transplant.
Researchers, lead by Dr. Bronwen Shaw, have discovered a hidden role of an additional allele that gives new insight on transplant outcomes. It was previously thought that this allele had no impact on transplant success, as it is often not matched between patient and donor. However, the new study revealed that it is possible to have permissive and non-permissive allele mismatches that have a tremendous impact on transplant outcomes.
For the study, the research team retrospectively analyzed over 5,400 transplants with a 10/10 match, discovering that only 20% of the patients had matches for this allele. Of the remaining patients, 31% ended up being permissive mismatches and 49% were non-permissive mismatches. The researchers found non-permissive mismatches to be linked to a substantially increased risk of overall mortality and severe acute Graft versus Host Disease when compared with permissive mismatches.
Dr. Shaw, concludes, "These findings provide a practical, clinical strategy for lowering the risk of death following an unrelated-donor blood stem cell transplant. It builds on the gold-standard which already exists for transplants and could be easily incorporated into the current framework transplant centers use when trying to find the best match."