Unrelated Donor

Alternative Donors

Unfortunately, the majority — or more than 70 percent — of children with diseases that could be cured with a bone marrow transplant will not have a matched related donor, the optimal donor for most transplants. For this reason, we have developed several clinical programs at UCSF to evaluate the benefit of using alternative donors when an optimal donor cannot be found. The three alternative donor programs are the following:

  • Unrelated Donors — When a related donor cannot be found and there is time to conduct a search, an alternative is to identify unrelated, healthy individuals who are histocompatible with the patient and are willing to donate bone marrow stem cells.
  • Umbilical Cord Blood — If a matched unrelated marrow stem cell donor is unavailable, another source of unrelated donor bone marrow stem cells that may be considered is umbilical cord blood (UCB). There are over three-dozen UCB registries worldwide which process and store cord blood collections from healthy babies. The cord blood, which is normally thrown away after a baby is born, contains a relatively large number of bone marrow stem cells. One potential advantage of using cord blood is that it does not need to be a perfect tissue match with the recipient. Disadvantages include the limited number of cells in a collection and relative delay in the recovery of marrow function post-transplant.
  • Haplocompatible Donors — As explained above, a biologic parent is always half matched, or haplocompatible, which means four out of eight HLA match, with his or her child since each child inherits half of the HLA genes from each parent. There is a 50 percent chance that any sibling will be haplocompatible with any other sibling.

The question often is asked as to whether a relative other than a sibling can be used as an HLA-matched donor for BMT. There is a very small chance, about one percent, that a parent may be closely matched with his or her child and can be used in the same manner as a matched sibling. In general, the chances that a sufficiently matched relative such as a cousin, uncle or grandparent will be found are so rare that the time and energy required usually do not warrant a search. However, under some circumstances, for example among certain ethnic groups or when the parents' families are related, it may be worth a careful extended family search. This will be addressed during the initial consultation.

For addtional information please see the UCSF Patient Education Page on Types of Pediatric Bone Marrow Transplant (BMT) Donors

UCSF Benioff Children's Hospitals medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your child's doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your child's provider.