155-P: EXTENDED B∗73 HAPLOTYPES CONFIRMED BY FAMILY STUDIES

Abstract

Aim The B∗73:01 allele has been a subject of interest since the mid-1990’s, when it was recognized as defining its own lineage, separate from all other HLA-B alleles (Parham et al). Recently, B∗73 has been implicated in the evolution of the Denisovans, an archaic human group, despite the fact that it has not yet been found in a Denisovan specimen (Abi-Rached et al). The theory that B∗73 haplotypes were acquired by introgression from Denisovans prompted us to search our current clinical database for extended B∗73 haplotypes, as demonstrated by family studies. Methods We searched our clinical database for any patients or family members that had been typed as B∗73 and looked for extended haplotypes which were confirmed within each family. Results From January 2000 to February 2013, a total of 10 families were identified with extended B∗73 haplotypes (Table 1). Four families had the haplotype A∗02:01, C∗15:05, B∗73:01, DRB1∗04:05, DQB1∗02:02. The six remaining families had unique extended haplotypes. C∗15:05 was present in every haplotype.[ Table 1 ] Conclusions Despite the diversity of the B∗73 haplotypes, in every case B∗73:01 was in strong linkage disequilibrium with C∗15:05. This was expected, because it has been estimated that worldwide, ∼ 98% of people carrying B∗73 also carry C∗15:05 (Abi-Rached et al). The only Denisovan individual who has been HLA typed was C∗15:05:02, C∗12:02:02, but lacked a B∗73:01 allele and was typed as B∗15:58, B∗35:63. It will be interesting to see if Class II typing for this archaic sample corresponds to any of the Class II alleles in the extended haplotypes in this study.