P227 Determination of HLA -A, -B and - DRB1 alleles and HLA-A -B haplotype frequencies in Egyptians based on family study

Abstract

Knowledge of allele and haplotype frequencies in human populations guides the search for an HLA- matched unrelated hematopoietic stem cell donor. A new algorithm developed by the National Marrow Donor program uses this information to predict the likelihood that a volunteer of a particular ethnicity will carry specific HLA alleles when typed at high resolution. In the present study, we determined the HLA-A,-B and -DRB1 alleles and HLA-A-B haplotype frequencies in Egyptians and compared them to various populations. Specificities of HLA-A, -B and -DRB1 loci were determined in 286 matched related donors of allogeneic hematopoeitic stem cell transplantation (AHSCT). Typing was performed using serologic and low resolution PCR- reverse sequence-specific oligonucleotide (rSSO) techniques. HLA-A-B haplotypes were defined by segregation analysis. The most frequent alleles for HLA class I HLA-A were: HLA-A2 (19.2%), A1 (15.8%), A30 (9.2%) and A24 (8.8%), for HLA-B, B41 (10.9%), B35 (10.2%), B44 (6%) and B50 (5.4%) and for DRB1∗13 (18.7%), ∗04 (15%) ,∗11(14.7%) and ∗03 (13.2%). The most frequent HLA-A-B haplotypes were: A24-B35 (3.8%), A2-B41 (3.4%), A1- B35 (3.4%) and A33-B14 (3.4%). This study report HLA allele and HLA-A-B haplotype patterns in Egyptians. These patterns were close to Jordanians and Lebanese and different from Saudi Arabians, Europeans, Americans and Asians. These data explain the difficulty of finding donors in world registries for Egyptian patients in need of a stem-cell transplant and highlight the need to for planning an Egyptian national unrelated donor registry to meet the demands of these patients.