Introduction: Argentina shows great cultural diversity due to several waves of Colombian and post- Colombian migrations into South America that merged with the ancestral population. The majority of Argentinians are of European descent (South American of European descent, SAE), “mestizo” (mixed European and Amerindian ancestry) and less represented  people of Native American descent (South American of Amerindian descent, SAA). Those migrations, in turn, increased HLA genetic diversity. To date, the admixture observed in Argentinian’s genotypes continues to be underspecified. We have previously shown differences in HLA allele frequencies of Umbilical Cord Blood (UCB) units taking into consideration donor’s reported ancestral origins and geographic distribution. Clear differences were observed in allele frequencies between the groups SAE and SAA but also in terms of geographic distribution, being SAA more represented in the North of our country. To further study such differences, we analyzed our samples within the reference populations according to HaploStats web application (http://www.haplostats.org),database that includes HLA haplotype frequency information relative to various global and ethnically specific populations.

Method: High resolution HLA A-C-B-DRB1-DQB1 typing from 451 Cryopreserved UCB units were  analyzed using HaploStats (HLA Dataset NMDP full 2011/Unphased Genotypes)  for all reference populations (AFA, API, CAU, HIS, NAM) with special interest in SCAHIS. Informed consent was collected from all donating mothers. Ethical approval was provided by the Ethics Committee of the Hospital de Pediatría Garrahan (No. 1109/2018).

Results: Frequencies in some/all reference populations were observed for 420 UCB units. Among  the 31 units, which failed to be represented in HaploStats database, 14 (45%) were reported as  SAA and 12/14collected in the North of our country; whereas only 7 (22.6%) were reported as SAE, all collected in the central region of Argentina. The remaining 10 units showed mixed or unknown origins: 2 mixture of both (SAA and SAE), and 8 of other mixed or Unknown origins, (6 of which include some SAA component).

Conclusion: Although HaploStats includes HLA haplotype frequency relative to various global and ethnically specific populations, our results showed that our ethnic minorities are still under-represented. Therefore, further analysis of HLA frequencies will help improve collection policies in the Public Cord Blood Bank to achieve its goal of  increasing our patient´s chance to find a compatible graft.