139-P: HLA-A, -B, -C, -DRB1, -DQA1, -DQB1 AND -DPB1 ALLELE FREQUENCIES IN A SAUDI POPULATION USING NEXT GENERATION SEQUENCING TECHNIQUE

Aim Next generation sequencing is a promising technique that can reveal the entire gene sequences and to the highest possible resolution without any phase ambiguities. We have employed this technique to investigate the frequencies of HLA-A, -B, -C, -DRB3/4/5, -DRB1, -DQA1, -DQB1 and -DPB1 in a Saudi cohort of healthy individuals. Methods We employed Next Generation Sequencing using the 454 genome sequence (GS) FLX System and Conexio Assign ATF 454 software to HLA genotype eight class I and class II loci. A total of 158 healthy Saudi adults were analyzed. Results The most frequent allele for HLA-A was HLA-A∗02:01:01:01 (13.6%); for HLA-B, HLA-B∗50:01:01 (15.8%); for HLA-C, HLA-C∗06:02:01:01 (18.7%); for HLA-DRB1, HLA-DRB1∗07:01:01:01 (26.6%); for HLA-DRB3/4/5, HLA-DRB4∗01:01:01:01 (44.0%); for HLA-DQA1, HLA- DQA1∗02:01(26.3%); for HLA-DQB1, HLA- DQB1∗02:01:01 (20.3%) and for HLA-DPB1, HLA- DPB1∗04:01:01 (33.2%). By studying Linkage Disequilibrium in this population the following two loci combinations were well represented; B∗50:01:01-C∗06:02:01:01; DRB1∗03:01:01:01-DQB1∗02:01:01; DRB1∗07:01:01:01-DQB1∗02:02. Two extended, conserved haplotypes were well represented in this population; A∗24:02:01:01-B∗08:01:01-C∗07:02:01:01- DRB1∗03:01:01:01-DRB3∗02:02:01-DQA1∗05:01:01- DQB1∗02:01:01-DPB1∗03:01:01 and A∗30:02:01-B∗53:01:01-C∗04:01:01:01-DRB1∗07: 01:01:01-DRB4∗01:01:01:01-DQA1∗02:01-DQB1∗03:03:02- DPB1∗04:01:01. Expected heterozygosity was significantly higher than observed. Conclusions We have used a highly informative technique for HLA typing of a Saudi healthy cohort to establish allele and haplotype frequencies. This should be of great importance for population studies, disease associations and future planning of the unrelated bone marrow donor registry.