Probability of finding a compatible sibling donor for bone marrow transplantation in Ireland

This study was undertaken to ascertain the frequency of compatible sibling donors for individuals requiring bone marrow transplantation (BMT) in Ireland. During the study period 1984-89, a total of 392 patients were HLA typed. Of these, 218 (55.6%) had a compatible sibling donor. Among the latter there were 4 degrees of compatibility: 168 (42.9%) were HLA-A,B,DR identical MLC unreactive: three (0.8%) were HLA-A,B,DR identical MLC reactive: 12 (3.0%) were HLA-A,B,DR identical (no MLC performed) and 35 (8.9%) were HLA-A, B identical (no DR or MLC performed). The leukaemias and aplastic anaemia comprised 82.9% of all requests. The majority of patients with acute myeloid leukaemia (64.4%), acute lymphoblastic leukaemia (51.2%), chronic myeloid leukaemia (73.9%) and aplastic anaemia (77.3%) had a potential sibling donor. Subsequently 144 of these patients had an allogeneic BMT, 79.9% of which were for patients with leukaemia (acute and chronic). This study found that there was a higher probability of finding a donor within the family than reported in most series. A clear relationship was demonstrated between family size and the likelihood of obtaining a HLA-identical sibling donor.