Bone Marrow Transplant - Children

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Finding or Becoming a Donor

A bone marrow or stem cell donor for your child will need to be matched by human leukocyte antigen (HLA) typing before your child can get a transplant. (You can read general information about HLA typing in our adult bone marrow transplant section.)

What Does Matching Mean?

It’s important to closely match the tissue of a donor with the tissue of a transplant recipient to decrease the chance that the recipient’s body will reject the transplanted cells (called host-versus-graft disease) or that the transplanted cells will attack the recipient’s tissues (called graft-versus-host disease). To match donors and recipients, doctors conduct tests to determine and compare their human leukocyte antigen (HLA) haplotype.

A haplotype is a set of closely linked genes that are inherited together. Children get one HLA haplotype from their mother and one HLA haplotype from their father. Tissue-typing tests look at five points on each HLA haplotype, for a total of 10 points. To be considered a good match for a transplant, the donor and recipient normally must match each other on at least nine of these 10 points.

The Search Begins

When doctors perform a stem cell transplant, their first choice is to use a donor who is related to the recipient and whose tissue is closely matched. Often relatives who are a match are willing to donate, and they usually can be enlisted in the process quickly. You may also want to read about what happens when a sibling is the donor.

Time can be of the essence when a transplant becomes necessary. If your child doesn't have a relative who is a close match, doctors search international volunteer donor banks for a close match. This takes more time, usually a matter of weeks to months. Though the delay is less than ideal, there is the possibility that the search will yield someone who matches closely enough to go forward with the transplant.

“Our Center has the most experience in the world doing unrelated donor transplants,” says Ann E. Woolfrey, MD, the director of unrelated donor programs for pediatric transplants at Fred Hutchinson Cancer Research Center. “For pediatric patients with malignant diseases, our unrelated donor transplants have the same outcome as our transplants using matched, related donors. Most places cannot achieve that outcome. One of our strengths is that since we have done so many unrelated transplants, we are very good at it.”

However, about 30 percent of patients overall who need a stem cell transplant can’t find a suitable donor and about 95 percent of racial-minority patients can’t find a match. In this case, alternative donors may be used.

The book “Preparing for Transplant,” which will be sent to you when you make an appointment for your child at Seattle Cancer Care Alliance, contains detailed information about donor options as well as information for donors.