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Bone Marrow Transplant


Allogeneic Hematopoietic Stem Cell Donor


Bone Marrow Transplant and Umbilical Cord Blood Registries


Individuals can chose to be potential marrow or peripheral blood HSC donors for other people. 

Donors are screened in a similar manner as when donating blood by

  • Submitting a blood sample for HLA-typing
  • Infectious disease testing. 

Alternatively, parents can donate their newborn’s umbilical cord blood to cord blood banks for public use.


HLA typing is done on these samples and the information stored in large worldwide registries that can be searched by transplant coordinators to find matches.

Generally accepted that for bone marrow and peripheral blood HSCTs the donor and recipient should be matched for 8/8 HLA alleles (i.e. both copies of HLA-A, B, C, and DRB1).  If this type of unrelated donor is found in the registry they are called a matched unrelated donor (“MUD”). 

The chance of finding a MUD is dependent upon an individual’s ethnic background. 

  • Caucasian recipients have about a 70% chance of finding a donor. 
  • Asian recipients about 50%
  • African-American about 30%. 
  • Mixed ethnic backgrounds can be particularly difficult to find a MUD.

Mismatched unrelated donor marrow (usually no worse than a 7/8 HLA-allele level match) may be acceptable only if other alternatives (e.g. cord blood, a matched relative) are not available.  These are very high-risk transplants.

With more umbilical cord blood being tested and stored the chance of finding an unrelated donor is improved.  Cord blood does not require a perfect HLA match since the stem cells are immunologically immature (less alloreactive).  Generally accepted that matching should be done at the HLA-antigen level for HLA-A and B and at the allele level for DRB1.  Umbilical cord is therefore matched out of 6. 

Ideally an umbilical cord HSCT is matched 6/6 with the recipient, but 5/6 and even 4/6 matches are often acceptable.

Bone Marrow Donors Worldwide is a voluntary collaborative effort of stem cell donor registries and cord blood banks whose goal is to provide centralized information on the HLA phenotypes and other relevant data of unrelated stem cell donors and cord blood units and to make this information easily accessible to the physicians of patients in need of a hematopoietic stem cell transplant



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