Molecular analysis of HLA allele frequencies and haplotypes in Baloch of Iran compared with related populations of Pakistan

3 , Abstract: The extreme polymorphism in different loci of the human leukocyte antigen (HLA) system has been used as an invaluable tool for anthropological studies. Determination of HLA allele and haplotype frequencies in different ethnic groups is useful for population genetic analyses and the study of genetic relationships among them. In the present study, molecular analysis of HLA-A, -B, -C, -DQA1, -DQB1 ,a nd-DRB1 genes has been used to assign HLA allele and haplotype frequencies in 100 unrelated healthy individuals from the Baloch ethnic group of Iran. The results were compared with Baloch and other ethnic groups in the neighboring Pakistan. The results of this study showed that the most frequent HLA class I alleles were A*02011 (20.2%), B*4006 (11.1%), and C*04011 (28.6%). The most common HLA class II alleles were DQA1*0101/2 (42.5%), DQB1*0201 (32%), and DRB1*0301 (29%). Three-locus haplotype analysis revealed that A*11011-B*4006-C*15021 (5.8%) and DQA1*0501- DQB1*0201-DRB1*0301 (22.1%) were the most common HLA class I and II haplotypes, respectively, in this population. Neighbor-joining tree based on DA genetic distances and correspondence analysis according to HLA-A, -B, -DQB1, and -DRB1 allele frequencies showed that Baloch of Iran are genetically very close to Baloch and Brahui of Pakistan. This may reflect an admixture of Brahui and Baloch ethnic groups of Pakistan in the Balochistan province of Iran. Iran with a population of over 60 million individuals and an area of about 1.6 million square kilometers is situated in south-western Asia and borders the Republic of Armenia, Azerbaijan, and Turkmenistan, as well as the Caspian Sea to the north; Turkey and Iraq to the west; the Persian Gulf and the Gulf of Oman to the south; and Pakistan and Afghanistan to the east. The oldest known civilization in Iran is Elam in the 10th century BC, but Arab and subsequent Mongol and Tatar invasions, each left its own impression on the subsequent develop- ment of different populations in this country (1). Iran also, as a country located between China and Europe, played a key role in connecting various cultures and civilizations that existed along the Silk Road (2).