SWAB A CHEEK, SAVE A LIFEc/o Gift of Life Bone Marrow Foundation Development Office 800 Yamato Road, Suite #101 Boca Raton, Florida 33431 Phone: 561.982.2919 Email:
The Search Process
Once the patient's physician has determined that an allogeneic bone marrow or blood stem cell transplant is the best course of treatment, a suitably matched donor must be identified. This is a multi-step process including immediate and extended family studies and an international unrelated donor search. Patients are encouraged to test immediate family members first. However, frequently time is a patient's biggest enemy. Thus, if a sibling match is not identified immediately, it is worthwhile to initiate an unrelated donor search concurrently with an extended family study.
It is important that patients maintain regular contact with the transplant center in order to obtain regular updates on the status of the donor search. If they are unable to perform this task, they are entitled to designate an advocate of their choosing, usually a close relative or friend to interface with the transplant center on their behalf.
IMMEDIATE FAMILY STUDY
Logic dictates that the most suitable match for a patient would be a family member.
- There is a 25 percent chance that a sibling will be a match. If the sibling is an identical twin, there will be a perfect match, referred to as syngeneic.
- Parents share 3 of 6 antigens with their biological children. This is referred to as haploidentical. In some cases, parents will share antigens in common with each other. In these circumstances, patients may share more than 3 of 6 antigens with a parent.
EXTENDED FAMILY STUDY
An extended family study is particularly useful among ethnic groups who tend to marry from within their own ethnic group from generation to generation. As typing information on relatives becomes available, experts can predict the likelihood of finding a related match and provide guidance with the related donor search. Possible strategies include determining which haplotype is less common and focusing on a specific branch of the extended family.
Sometimes, when a patient does not have any immediate or extended family, or if it is clear that their HLA typing is uncommon, engaging in genealogical research may be helpful. By tracing familial roots back several generations, one may be able to locate previously unknown descendants. Constructing family trees starting with one's ancestors can be beneficial, and there is family tree software available on the market that can simplify the task of tracking this information. In terms of research, there are numerous resources available, including genealogical societies and searchable databases on the World Wide Web. If a patient was adopted, this research becomes crucial in order to find potential siblings or other close relatives. This research will require the cooperation of adoption agencies, hospitals, and local governmental.
UNRELATED DONOR SEARCH
Coordinators at transplant centers should have access to the Bone Marrow Donors Worldwide (www.bmdw.org), a collaborative effort of 51 registries in 37 countries. The database contains the phenotypes of more than twelve million prospective bone marrow and blood stem cell donors. After obtaining a summary report, the coordinator can narrow the search to a few specific registries that have potential matches, and submit to those specific registries, according to the five-step process outlined in the next section.
Step 1: Preliminary Search
According to the standards and practices promulgated by the World Marrow Donor Association (www.worldmarrow.org), international registries perform preliminary searches at no charge. The transplant center's search coordinator or the patient's local physician initiates the process on behalf of the patient. Searches are considered preliminary until the first request for additional testing of any donor. This step initiates “search activation”.
Step 2: Search Activation
The first request for additional testing of any donor constitutes a step known as “activation”. Only transplant centers can activate a search on behalf of a patient. These are accredited hospitals with sufficient experience in allogeneic transplantation, including specialized facilities and staff. Larger centers may be designated Comprehensive Cancer Centers by the National Cancer Institute. If the patient has not yet selected a hospital to manage his / her search, this must be done before activation can take place. Patients should understand that they do have a right to transfer their search to another hospital at any time.
Most registries charge an activation fee to formalize a search. Patients can obtain this information from the transplant center's unrelated donor search coordinator. Generally, there are two types of test requests that will be performed at this stage: Class II (DR) typing and Confirmatory Typing (CT). Roughly 50 percent of the donors in the worldwide registries are not fully ABDR typed (Class I and II). If no fully ABDR matched donors are identified initially, coordinators must request DR typing of any potential matched donors who are only AB typed. In many cases, donors identified in the Registry are DR typed by low resolution DNA methodologies, and require high resolution DNA typing to obtain more definitive results.
Step 3: Donor Selection
The transplant center chooses suitably matched donors on behalf of their patients. Ideally, donors should match their patients on A, B and DR antigens, using DNA-based typing techniques. If no perfectly matched donors are identified, some centers may request mismatched donors (five of six antigens). Other factors that are taken into consideration include matching on other loci (such as the C locus), the donor's sex, number of pregnancies if female, transfusion history, age, size and availability. The Registry also takes several other factors into consideration before approving the donor selection, including recipient age, disease, stage, and transplant center qualifications.
Step 4: Donor Workup
All donors requested for workup attend an information session in order to receive a thorough education. After counseling, all donors must sign a form called the Intent to Donate before they can proceed further. This constitutes a moral obligation on the part of the donor, and represents the Registry's assurance that “informed consent” has taken place. All donors receive a thorough physical exam, including a health history screening, blood work, electrocardiogram, chest x-ray and repeat Infectious Disease Markers. This is performed to protect the donor as well as the potential recipient. If the volunteer is cleared, the donation is scheduled.
Step 5: Bone Marrow or Blood Stem Cell Collection
For a description of the donation process, please read Step to Become a Donor.