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.

GENEALOGICAL RESEARCH
Sometimes, when a patient does not have any immediate or extended family, or if it is clear the 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 agencies, perhaps with the guidance of private investigators.

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 over eight 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”.