Bulgarian Bone Marrow Donors Registry—past and future directions
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- Zlatev, A., Ivanova, M., Michailova, S. et al. Cell Tissue Bank (2008) 9: 347. doi:10.1007/s10561-007-9046-z
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Recently Bulgarian Bone Marrow Donors Registry (BBMDR) has been established and since August 2005 it has been a member of Bone Marrow Donors Worldwide. Currently the number of healthy donors included in the BBMDR is relatively low. All donors included in the BBMDR are typed for HLA-A, -B, -DRB loci. Phylogenetic analysis based on HLA allele frequencies shows that Bulgarians were characterized with closest genetic similarity to Macedonians, Greeks, Romanians, Cretans and Sardinians in comparison to the other European and Mediterranean populations. On the contrary the second largest ethnic minority–the Roma were the closest to the other Roma populations and North Indians. These differences were due to the predominance of alleles and haplotypes that are specific for the Asian and the other Roma populations. These specific genetic profiles in the Bulgarian ethnic minorities justify the need of an adequate representation of minorities in BBMDR. Future directions for BBMDR development are discussed, including an increase of the total number of donors and these for ethnic minorities, as well the enhancement of the level of resolution of the HLA typing for the donors in the registry.
KeywordsBulgarian Bone Marrow Donor RegistryBulgariansHLA allelesHLA haplotypesRoma
Haemopoietic stem cells transplantation is modern and highly efficacious method of treatment of hematological malignancies, primary immune deficiencies and recently other diseases. The accomplishment of allogeneic hemopoietic stem cells transplantation is restricted due to need for finding an HLA identical donor. Identification of completely HLA matched donors in the family is possible for only a small proportion of patients. That necessitated the establishment registries of healthy subjects, in order to provide HLA matched haemopoietic stem cells for the patients requiring bone marrow transplantation. Currently about 63 different registries, including more than 10 million voluntary donors are established worldwide and are included in World Marrow Donor Association. The majority of these registries are located in Europe (particularly in West and North Europe) and North America. The number of registries in Eastern Europe is still limited and generally these registries are relatively small. The Bulgarian Bone Marrow Donors Registry (BBMDR) was established within Central Laboratory of Clinical Immunology in 2002 and since August 2005 it has been a member of Bone Marrow Donors Worldwide (BMDW).
Donor management activities: recruitment of volunteer stem cell donors, storage and maintenance of donor data and exchange of data with BMDW, handling of national and international requests for unrelated stem cell donors from BBMDR file and distribution of blood and DNA samples for confirmatory typing.
Patients search activities: identification of unrelated stem cell donors in the national and international registries for Bulgarian patients in need of transplantation for whom no suitable donor could be identified in the family
Coordinating activities: processing requests for donors originating from the country or emanating from abroad and coordinating activities of donor and transplant centers
Consultancy activities: providing immunogenetic advise about the feasibility of finding a suitable donor and coordination of the search process
Characteristics of unrelated stem cell donors in BBMDR
The most frequent HLA-A-B-DRB1 haoplotypes in the BBMDR
Other populations where the haplotype has been found
A*02 B*18 DRB1*11
Greeks, Sardinians, Italians, French, Portuguese, Romanians, Czech, Slovenians, Croatians, Macedonians
A*01 B*08 DRB1*03
A*24 B*35 DRB1*11
Greeks, Cypriot, Sardinians, Italians, Spanish, Romanians
A*02 B*51 DRB1*11
Greeks, Cypriot, Sardinians, Italians, French, Danish, Portuguese, Slovenians, Croatians, Hungarians
A*02 B*51 DRB1*16
A*02 B*27 DRB1*16
A*01 B*57 DRB1*07
Western European populations
A*03 B*18 DRB1*16
A*11 B*07 DRB1*15
A*23 B*44 DRB1*07
A*24 B*35 DRB1*04
A*26 B*38 DRB1*04
Turkish, Macedonians, Jewish
A*24 B*51 DRB1*11
Cypriot, Italians, French, Spanish, Slovenians, Croatians
A*03 B*18 DRB1*16
This distinct genetic profile emphasized the need to represent correspondingly minorities in the bone marrow donor registries. Ethnic composition of population in Bulgaria is as follow: Bulgarians—87%; Turkish—8%; Roma—4% and others—1%. In BBMDR so far are represented mainly Bulgarians (94%), while the proportion of Roma and Turkish is relatively smaller (2% and 4% respectively) and therefore the number of donors from these ethnic groups should be increased.
Search activities of BBMDR
Considering the small number of donors recruited so far, one of the main goals of the BBMDR would be to increase the number of voluntary donors by establishment of national network for donor recruitment. Preliminary statistical analysis showed that considering the size of our population and specific genetic background the optimal number of donors in the registry would be 5000. Due to specific genetic characteristics of the Bulgarians, for some patients lacking HLA matched donor in the family it is difficult to find donor in the international registries. Therefore it is necessary to recruit donors with rare alleles and haplotypes in order to increase the probability patients from ethnic minorities to be transplanted. Other important tasks of BBMDR is the improvement of BBMDR database and information system and integration in the European Marrow Donor Information System (EMDIS), accreditation according to WMDA standards, and the improvement of stem cells exchange between BBMDR and other registries within BMDW according to national and international regulations.