The genetic heterogeneity of Arab populations as inferred from HLA genes

Abstract

This is the first genetic anthropology study on Arabs in MENA (Middle East and North Africa) region. The present meta-analysis included 100 populations from 36 Arab and non-Arab communities, comprising 16,006 individuals, and evaluates the genetic profile of Arabs using HLA class I (A, B) and class II (DRB1, DQB1) genes. A total of 56 Arab populations comprising 10,283 individuals were selected from several databases, and were compared with 44 Mediterranean, Asian, and sub-Saharan populations. The most frequent alleles in Arabs are A*01, A*02, B*35, B*51, DRB1*03:01, DRB1*07:01, DQB1*02:01, and DQB1*03:01, while DRB1*03:01-DQB1*02:01 and DRB1*07:01-DQB1*02:02 are the most frequent class II haplotypes. Dendrograms, correspondence analyses, genetic distances, and haplotype analysis indicate that Arabs could be stratified into four groups. The first consists of North Africans (Algerians, Tunisians, Moroccans, and Libyans), and the first Arabian Peninsula cluster (Saudis, Kuwaitis, and Yemenis), who appear to be related to Western Mediterraneans, including Iberians; this might be explained for a massive migration into these areas when Sahara underwent a relatively rapid desiccation, starting about 10,000 years BC. The second includes Levantine Arabs (Palestinians, Jordanians, Lebanese, and Syrians), along with Iraqi and Egyptians, who are related to Eastern Mediterraneans. The third comprises Sudanese and Comorians, who tend to cluster with Sub-Saharans. The fourth comprises the second Arabian Peninsula cluster, made up of Omanis, Emiratis, and Bahrainis. It is noteworthy that the two large minorities (Berbers and Kurds) are indigenous (autochthonous), and are not genetically different from “host” and neighboring populations. In conclusion, this study confirmed high genetic heterogeneity among present-day Arabs, and especially those of the Arabian Peninsula.

HLA class I allele lineages and haplotype frequencies in Arabs of the United Arab Emirates

“…In regard to the HLA‐B allele lineages in the UAE, the three most frequent were B*51 (0.163), B*08 (0.137) and B*50 (0.137), which is similar to the HLA‐B frequencies for 373 Arabs from the UAE reported by Valluei et al (). HLA‐B*51 also occurs at high frequency (>0.15) in the population of Saudi Arabia (Hajeer et al, ), Oman (Albalushi et al, ) and Iraq (Abbas, ), is intermediate (0.10 to 0.15) in Ghana, Lebanon, Libya, Jordan and Europe (Hajjej et al, ), and relatively low (<0.10) in Singapore, Indonesia, Australia and South Africa (Verity, Wallace, Vaughan, & Stanford, ). Although the prevalence of Behcet's disease in UAE Arabs, and particularly the Bedouin, is not known, it has been associated strongly with HLA‐B*51 in the population of Turkey, Israel, Iran, Saudi Arabia, Iraq and Japan, and those along the historic Silk Road (Keino & Okada, ).…”

“…A recent meta‐analysis of HLA class I and class II genes of 100 populations from 36 Arab and non‐Arab countries by Hajjej et al () confirmed the genetic heterogeneity of some Arab populations and suggested that Arabs could be stratified into four groups: (1) North Africans (Algerians, Tunisians, Moroccans and Libyans), (2) Levatine Arabs (Palestinians, Jordanians, Lebanese and Syrians), and two different Arabian Peninsula clusters, (3) a Saudis, Kuwaitis and Yemenis cluster, and (4) an Omanis, Emiratis and Bahrainis cluster. In our phylogenic analysis (Figure and Figure ), the Saudi, UAE and Omani populations of the Arabian Peninsula were in the same clade as 4 different Pakistani sub‐populations and separate to an adjoining clade of Jordanians, Israeli Jews, Tunisians and Moroccans.…”

“…Nine countries and a marked ethnic diversity due to a large influx of Asian immigrants characterize the Arabian Peninsula where numerous migrations between Africa, Europe and Asia have occurred since ancient times. Despite this heterogeneity, genetic anthropology studies of the polymorphic HLA genes of the indigenous Arabs are rarely reported (Hajjej, Almawi, Arnaiz‐villena, Hattab, & Hmida, ). There are recent studies on genotyping of HLA class I and class II loci in the people of Saudi Arabia (Hajeer et al, ), Oman (Albalushi et al, ) and Iraq (Abbas, ), but little information about the HLA class I allele and haplotype frequencies in the Arabs of the United Arab Emirates (UAE) and those along the eastern coast of the southern end of the Arabian Peninsula.…”

Phlebotomus papatasisand fly salivary protein diversity and immune response potential in Egypt and Jordan populations

“…We also identified the MHC class II alleles expected to recognize the salivary protein epitopes and investigated the predominant alleles of human populations living in Egypt and Jordan. The MHC class II alleles with strong binding affinities for PpSP12 that are also prevalent in Egyptian and Jordanian human populations include: DRB1_0301, DRB1_040X, DRB1_110X, DRB1_1301, and DRB1_150X [67–69]. The MHC class II alleles identified for PpSP14 include: DRB1_1101, DRB1_0301, DRB1_040X, DRB1_11XX, DRB1_13XX, DRB1_15XX, and to a lesser extent DRB1_070X [67–69].…”

“…The MHC class II alleles with strong binding affinities for PpSP12 that are also prevalent in Egyptian and Jordanian human populations include: DRB1_0301, DRB1_040X, DRB1_110X, DRB1_1301, and DRB1_150X [67–69]. The MHC class II alleles identified for PpSP14 include: DRB1_1101, DRB1_0301, DRB1_040X, DRB1_11XX, DRB1_13XX, DRB1_15XX, and to a lesser extent DRB1_070X [67–69]. The six remaining salivary proteins are predicted to bind to MHC class II alleles with varying affinity.…”