Finding and Matching a Donor
Finding a Matched Donor
The stem cells may come from a brother, sister, cousin, parent, an unrelated individual who has been matched to you, or from yourself. If you are having an autologous transplant, you will receive your own stem cells. If you are having an allogeneic transplant, you will receive matched stem cells from someone else.
To be considered a match, the donor must share your tissue type. Because we inherit our tissue type, like we inherit our eye color or height, each of our siblings has a one-in-four chance of matching us. Parents, offspring, aunts, uncles, and cousins rarely are well enough matched to be a donor for an adult recipient.
When a sibling is not available to be a donor and stem cells from a healthy donor is required, a matched unrelated donor search will be initiated. The chances of any two unrelated people sharing the same tissue type are between 1-in-100 to greater than 1-in-5 million.
Worldwide, more than 6 million volunteers are registered as stem cell donors. Once a donor is identified, a very detailed set of guidelines must be followed to insure that the donor is fully counseled, able to provide informed consent, and medically suited to proceed.
Match Criteria for Unrelated Stem Cell Donors
There are two levels of testing in identifying an unrelated stem cell donor for you. The first level of testing is basic tissue typing. Volunteers who join donor registries are often tissue typed using low resolution DNA typing. A world-wide donor search is run through national and international donor registries. Potential donors are those whose tissue types are similar to your tissue type.
The second level of testing is confirmatory typing. If one or more donors are identified who are likely to share your tissue type, a request is made for those volunteers to have a blood sample drawn and shipped to our lab. We repeat the volunteer's HLA-A, B, C and DRB1 typing using high resolution DNA technology. At this level, tissue types are more specifically defined. The donor's blood is also tested for infectious diseases.
We will accept two groups of unrelated donors:
Group 1 = Unrelated donors who share all of your HLA-A, B, C & DR alleles. All alleles must be defined using DNA technology.
Group 2 = Unrelated donors who mismatch at only one HLA-A, B, C or DRB1 antigen or allele. All other HLA-A, B, C and DRB1 alleles must match.