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15-W
S20
Abstracts
Tuesday, October 17, 2006 2:00 PM – 3:30 PM Workshop 3: Case Studies: Hematopoietic Stem Cell and Cord Blood Transplant New this year - the winner of the case study award will be determined onsite by a panel of individuals. 15-W
SOUTH-AMERICAN ALLELES IN THE CARIBBEAN AND FINDING A MATCH BY EXTENDED FAMILY TESTING OF A PATIENT WITH TWO RARE HLA-A ALLELES Marcelo Fernandez-Vina, Susan Sheldon, Weicheng Zhao, Heman Patel, Edward Guerrero, Pedro Cano. Laboratory Medicine, MD Anderson Cancer Center, Houston, TX, USA Aim: In order to find prospective bone-marrow-transplant candidates for patients with unusual alleles, it is essential to have accurate knowledge not only of the distribution of these alleles in various populations, but also of the linkage disequilibrium of these alleles. Only rare alleles present in conserved haplotypes have any prospects of finding a fully HLA-matched unrelated fonor. This case presentation aims to illustrate these principles. Methods: Intermediate-resolution SSO is the method of choice in searching for related donors in bonemarrow transplantation and in making the final selection. Nevertheless, when a complete family genotype analysis is not possible and the four family haplotypes have not been distinctly identified, high-resolution typing is necessary. DPB1 typing is also very useful in this setting as long as it can reveal the different identity of two haplotypes that appear to be very similar and even identical, as it is shown in this case. Scope: A candidate for allogeneic bone-marrow transplantation from Puerto Rico had the following genotype: (A*0204-B510101-Cw*1502-DRB1*0411-DRB4*0103-DQB1*0402-DPB1*0402) (A*0217B510101-Cw*1502-DRB1*040301-DRB4*0103-DQB1*030201-DPB1*040101). No HLA-identical siblings were available. Extended family testing was performed and a son of the patient was found to share the A*0217 haplotype, and, in addition, had another A*0204 haplotype very similar to the patient’s, only differing in the DPB1 allele (A*0204-B510101-Cw*1502-DRB1*0411-DRB4*0103-DQB1*0402-DPB1*1401). These and other South American HLA-A alleles, such as A*0211 and A*0222, were found multiple times in subjects from Puerto Rico and Cuba. Conclusions: Although the indegenous populations of the Caribbean Islands are thought to be extinct, the aboriginal genes prevail in the modern populations of the islands. Alleles considered rare and restricted to Northern South America, such as A*0204, A*021701, A*0211 and A*0222, happern to be found regularly in Caribbean populations. This observation has important implications in searching for donors with rare alleles. In the case presented here the rare allele A*0204 was found in two different haplotypes in two family members. This case presentation ilustrates how rare alleles can be found in particular subpopulations in so far as it is present in a conserved haplotype. Expansion of donor pools in bone-marrow registries of these minorities and details on the geographic and ethnic origin may dramatically increase the chances of finding closely HLA-matched donors for patients with rare alleles.
Abstracts
Tuesday, October 17, 2006 2:00 PM – 3:30 PM Workshop 3: Case Studies: Hematopoietic Stem Cell and Cord Blood Transplant New this year - the winner of the case study award will be determined onsite by a panel of individuals. 15-W
SOUTH-AMERICAN ALLELES IN THE CARIBBEAN AND FINDING A MATCH BY EXTENDED FAMILY TESTING OF A PATIENT WITH TWO RARE HLA-A ALLELES Marcelo Fernandez-Vina, Susan Sheldon, Weicheng Zhao, Heman Patel, Edward Guerrero, Pedro Cano. Laboratory Medicine, MD Anderson Cancer Center, Houston, TX, USA Aim: In order to find prospective bone-marrow-transplant candidates for patients with unusual alleles, it is essential to have accurate knowledge not only of the distribution of these alleles in various populations, but also of the linkage disequilibrium of these alleles. Only rare alleles present in conserved haplotypes have any prospects of finding a fully HLA-matched unrelated fonor. This case presentation aims to illustrate these principles. Methods: Intermediate-resolution SSO is the method of choice in searching for related donors in bonemarrow transplantation and in making the final selection. Nevertheless, when a complete family genotype analysis is not possible and the four family haplotypes have not been distinctly identified, high-resolution typing is necessary. DPB1 typing is also very useful in this setting as long as it can reveal the different identity of two haplotypes that appear to be very similar and even identical, as it is shown in this case. Scope: A candidate for allogeneic bone-marrow transplantation from Puerto Rico had the following genotype: (A*0204-B510101-Cw*1502-DRB1*0411-DRB4*0103-DQB1*0402-DPB1*0402) (A*0217B510101-Cw*1502-DRB1*040301-DRB4*0103-DQB1*030201-DPB1*040101). No HLA-identical siblings were available. Extended family testing was performed and a son of the patient was found to share the A*0217 haplotype, and, in addition, had another A*0204 haplotype very similar to the patient’s, only differing in the DPB1 allele (A*0204-B510101-Cw*1502-DRB1*0411-DRB4*0103-DQB1*0402-DPB1*1401). These and other South American HLA-A alleles, such as A*0211 and A*0222, were found multiple times in subjects from Puerto Rico and Cuba. Conclusions: Although the indegenous populations of the Caribbean Islands are thought to be extinct, the aboriginal genes prevail in the modern populations of the islands. Alleles considered rare and restricted to Northern South America, such as A*0204, A*021701, A*0211 and A*0222, happern to be found regularly in Caribbean populations. This observation has important implications in searching for donors with rare alleles. In the case presented here the rare allele A*0204 was found in two different haplotypes in two family members. This case presentation ilustrates how rare alleles can be found in particular subpopulations in so far as it is present in a conserved haplotype. Expansion of donor pools in bone-marrow registries of these minorities and details on the geographic and ethnic origin may dramatically increase the chances of finding closely HLA-matched donors for patients with rare alleles.