The term “Arab” is a major panethnic group that includes people from various ancestral origins, religious backgrounds and historical identities. The Arab League is a cultural and ethnic union of 22 member states, with over 357 million people from both Asia and Africa. The term “Arab” includes all populations speaking the Arabic language and living in the vast area extending from south of Iran in the east to Morocco in the west including parts in the southeast of Asia, East and West of Africa. The Middle East region (ME) includes Arab and non-Arab countries, and is home to ~10% of the world’s population (reference). Most Arabs follow Islam, and Christianity is the second largest religion with over 15 million Christians. There are smaller but significant religious minorities, e.g. Druze and Jews, and a number of non-Arabs ethnic minorities, e.g. Berbers and Kurds (reference). The Middle East encompasses significant ethnic, linguistic and genetic diversity. The population in this region have extensively admixed with the population of African continents, Asia and Europe which resulted in current ME rich diversity. The ME has been a central hub of human migration and population admixture.
The Arabian Peninsula situated at the nexus of Africa, Europe and Asia has been implicated in the early human migration route known as the “Out of Africa” and in early inter-continental trade routes. Historically, the population of Arabian Peninsula comprises early settlers originating from regional tribes particularly from Saudi Arabia and Persia and including nomadic Arabs (Bedouin) of the desert, living on the fringes of the Arabian Peninsula (reference). It is estimated that 25 to 60% of all marriages are consanguineous in the Arab world. The population of the region is characterised by large family size, high maternal and paternal age and a high level of inbreeding (consanguinity estimated rates in Bahrain 46%, Kuwait 64% and Saudi Arabia 67%) thus, several genetic diseases are common in the Arab world (reference). This geographical and social organization might be expected having effects on patterns of genetic diversity, particularly in the Arab world. The high level of endogamy in the region makes the population of ME ideal to further study its genetic landscape.
History of populations and population genetics studies
i. Saudi Arabia
North of Africa is known for its complex population history and its periodic gene flow with neighbouring Middle East populations across the Suez Isthmus toward the Levant, and with European populations across the Strait of Gibraltar toward the Iberian Peninsula (reference). Events changed dramatically with the rise of Islam in Arabia during the 7th century in deed in a short span of time Arabs built a military and cultural empire that extended from Afghanistan in the east to the Iberian Peninsula in the west. A complete Arabization occurred later in the North Africa with the Bedouin Bani Hilal invasion in the 11th centaury.
The Kingdom of Saudi Arabia is the largest country in the Arabian Peninsula, the crossroads between Africa and Eurasia, and its population has been enriched by gene flow over generations. Its 33 million population is dense in the cities, while very low density is observed in its large deserts areas (reference).
A study conducted on mitochondrial DNA in Saudi population showed greatest similarity to Bedouin from Najaf and Yemen, and to Levantine populations. Nearly all western Asian haplogroups were detected and had only a small Sub-Saharan Africa component (7%), north African contribution (5%) and small Indian influence (3%) (reference). Regarding the autosomal Y-STRs, a recent study comparing five geographical regions in Saudi Arabia (North, South, Central, East and West) reveals striking differences, with low diversity in the central and Northern regions , and high diversity in the East and West. The author suggests that these patterns likely reflect the geographical isolation of the desert heartland of the Arabian Peninsula and the proximity to the sea of the Eastern and Western areas (reference).
The Kingdom Bahrain is a small island state (the third smallest country in Asia) located in the western shores of Persian Gulf. Saudi Arabia lies at the west while the Qatar is to the south east. The population of Bahrain is almost 1.5 million, half of which consists of native Bahrainis while the other half consists of expatriates mainly from Arab leagues member states, mainly from Iran and southwest Asia (reference). Bahrain is the site of ancient Dilmun civilization, it was converted to Islam in 623 AD and was occupied by the Portuguese from 1521 to 1602, until their explulsion by Shah Abbas I of the Safavid dynasty under the Persian Empire. Shia Bahrainis are the majority of the population with two main ethnic groups: Ajam and Baharna. Most of Shia Bahrainis in the country belong to Baharna ethnic group, while the Ajam are ethnic Persian Shias whose ancestors arrived in Bahrain in the early 20th century as laborers and merchants.
There is almost a complete absence of genetic studies. The only population genetic research, conducted in 2013 and using Alu insertion polymorphisms, showed that Bahrainis ancestors were mainly emigrants from Saudi Arabia and Iran, reaching the later component 69.2% of the current genetic pool of Bahrainis (reference).
Kuwait situated at the north-western part of Arabian Peninsula,the northern tip of Persian Gulf, is bordered by Iraq in the north and Saudi Arabia to the south. Of the 4.2 million Kuwaiti population around 70% account for expatriate, mainly from Saudi Arabia, Iran and South Asia. Kuwait has a cosmopolitan population of mosaic representing most Arab tribes including other large and small ethnic minorities (reference). There is a strong evidence of genetic similarity of Kuwait with its neighbouring Arab populations. The settlements from Saudi Arabia, Persia and Arabian Peninsula and subsequent admixtures have shaped the genetics of current Kuwait populations. A study conducted in Kuwaiti population suggests extensive admixture with population from Africa, Europe and Asia (reference). Genetic features characterise Kuwaiti population into to following three migratory subgroups: the first group is largely of West Asian ancestry, representing Persians with European admixtures, the second group is predominately of city-dwelling Saudi Arabian tribe ancestry and the third group includes most of the tent-dwelling called Bedouins characterised by presence of 17% African ancestry (reference).