P224 Diversity of alleles and haplotypes of HLA class I and class II in Saudi population

Abstract

Aim Human Leukocyte Antigens (HLA) play an important role in host immune responses to infectious pathogens, bone marrow and organ transplantation, cancer and autoimmune diseases. HLA association studies have shown that homozygosity was associated with worse clinical outcomes of transfusion associated-graft versus host disease (TA-GvHD). Here we conducted a retrospective study of HLA class I and class II genes homozygosity at allelic and haplotype levels in patients and healthy donors genotyped from 2012 to 2016 in a tertiary hospital at the capital of Saudi Arabia. Methods About 2773 cases were retrospectively analyzed for HLA-A, -B, -C -DRB1 and DQB1 homozygosity at allelic and haplotype levels. HLA molecular typing was performed using a commercial Sequence-Specific oligonucleotides (SSO) kit and following the manufacturer instructions (rSSO; One Lambda, Canoga Park, CA). Statistical analysis was done with Fisher’s exact test (two-tailed). The analysis was performed on Stata package. Results In contrast to other populations, we were able to identify only 46 HLA class I and 18 class II alleles demonstrating a very low genetic diversity in Saudi population. A total of 15 HLA-A, 20 HLA-B, 11 HLA-C, 13 HLA-DRB1 and 5 HLA-DQB1 alleles have been identified. In class I, the highest homozygosity is found in locus C followed by A and B (21.3% > 17.1% > 15.5%; p 20.3%; p Conclusions We found low genetic diversity of both class I and II alleles and haplotype in Saudi population which would have a significant impact in shaping the transplantation practices, transfusion associated graft versus host disease practices and host-pathogen interactions in the population.