Published online by Cambridge University Press: 10 March 2009
Bone marrow transplantation has become an accepted treatment for severe aplastic anemia, acute myelogenous leukemia, and acute lymphocytic leukemia (20;35). Less commonly thalassemia (23), multiple myeloma (25), severe combined immune deficiencies (10), and chronic granulocytic leukemia (14) are also treated with marrow transplantation. Most donors are siblings whose HLA phenotype is identical to the patient's. Such donors, however, are available to only one third of patients (6;16;27;28;35). In the absence of an HLA-identical sibling, partially matched, haplo-identical, related donors (differing by only one major histocom-patibility antigen) can be found for another 7% of patients (1;6;27;37). A variety of lower quality matches also can be found but have not been used extensively. Advances in tissue typing and the treatment of graft versus host disease now allow physicians to consider matched unrelated individuals as potential donors when a suitable related donor is not available (11;12;13;15;17;22).