123-P: HLA DIVERSITY IN A CHILEAN POPULATION

Aim A hematopoietic stem cell transplantation program in Santiago, Chile affiliated with St. Jude Children’s Research Hospital referred 190 patients and their family members for HLA typing between 2000 and 2011. Methods These individuals were studied for HLA specificities by the use of sequence-specific oligonucleotide primers (SSP), sequence-specific oligonucleotide probes (SSO) and DNA sequencing. Haplotype assignment could be made unambiguously in all cases from family studies. Results The expectation of the referring center was that this group consisted largely of those of western European origin. HLA typing of the large proportion of this referred group indicated that although 70 - 80 % was similar to populations found in western Europe, a substantial number demonstrated alleles not found in western Europeans and which were initially described in native South American populations. For example, of 35 patient samples positive for HLA-A ∗ 68, 34 (97%) were found to be HLA-A ∗ 68:01:02 by DNA sequencing, a variation described in native South American populations. HLA-A ∗ 68:23 was identified in 8 unrelated individuals in this group of 719 patients and family members. This would indicate that this unusual allele would meet the criteria for a common and well-documented allele in this population. Alleles of HLA-A ∗ 02, A ∗ 24, as well as other A ∗ 68 alleles not commonly seen in those of western European heritage were also found. Eleven HLA-B ∗ 35, six HLA-B ∗ 39 and five HLA-B ∗ 51 alleles first described in native South American populations were also found in HLA typing of this group from Chile. HLA-DRB1 ∗ 04:07 was shown in 87 and HLA-DRB1 ∗ 08:02 in 55 of these 719 individuals. Conclusions Unrelated donor registries in Argentina and Brazil have recently formed cooperative agreements with the National Marrow Donor Program and can be expected to be beneficial for those patients from South America requiring unrelated hematopoietic stem cell donors.