HLA Class I and Class II Genes Distribution of the Sistanis in Iran

Background: The high polymorphism in the human leukocyte antigen (HLA) genes can be used as an identity of individuals to compare with other populations. This extreme polymorphism in the HLA system is accountable for the differences in alleles and haplotypes among ethnic groups, populations, and the inhabitants of many regions. Objective: To define the frequency of HLA alleles and haplotypes among the Sistanis, Sistani/Zaboli population in Iran. Methods: In this study, genotyping of class I (A, B, C) and class II HLA (DRB1, DQA1, DQB1) loci were determined in 90 unrelated Iraninan Sistani people and the results were compared with 474,892 HLA chromosomes from a diverse worldwide population. Results: The highest frequently observed alleles in this study were A*02:01, B*35:01, C*12:03, C*06:02, DRB1*11, DQA1*05:05, and DQB1*03:01. Furthermore, the most frequent 3-locus haplotypes were A*02:01- B*50:01*C*06:02, DRB1*11-DQB1*03:01-DQA1*05:05, and A*02:01-B*50:01- DRB1*07. The most occurring 4-locus haplotypes were A*02:01-B*50:01-C*06:02- DRB1*07 and A*02:01-B*50:01-DRB1*07-DQB1*02:01. A*02:01-B*50:01-C*06:02- DRB1*07-DQB1*02:01 and A*02:01-B*50:01-C*06:02-DRB1*07-DQB1*02:01- DQA1*02:01 were determined to be the predominant 5- and 6-locus haplotypes, respectively. The heat maps and multiple correspondence analyses based on the frequency of HLA alleles showed that Sistanis share a common genetic inheritance with other Iranian ethnic groups such as the people from Yazd and Fars except some differences with Baluchis, Iranian Jews, Lurs of Kohgiluyeh/Buyerahmad, and Arabs of Fars, which may arise from the admixture of these groups or with foreign subgroups over centuries, and also a close relatedness with some European populations. Conclusion: These data could be useful for finding better donor matches for organ transplantation among Sistanis or other related Iranian ethnic groups, epidemiological studies of HLA-associated diseases, handling HLA genomics and mapping the migration pattern of different ethnic group.