A similar study was performed by Ottinger from Essen, showing similar results to the Seattle study. The chance of finding an identical or 1 antigen mismatched family donor can be calculated with a computer program, so this may help you in the decision making whether to perform extended family typing or not. Extended family donors are often better matched than unrelated donors. The reason is that they have at least one haplotype genetically identical to the patient, and that there may be some higher match grade for the minor histocompatibility antigens. An extended family donor could be the only donor for the patient.
Ethical considerations have to be taken into account.
Extended family donors should be volunteer donors.