Newswise — A first of its kind genetic study confirms the history of the Druze community: The community began to form genetically in the 11th century AD, and there has since been no genetic impact of other ethnic groups on the community. This is according to a new study conducted by a team of researchers led by Prof. Gil Atzmon of the University of Haifa, Prof. Jamal Zidan of the Ziv Medical Center, Zefat, and Prof. Eitan Friedman of the Chaim Sheba Medical Center, Tel Hashomer. “This is the first genetic study to discover that the Druze community has genetic origins in the 11th century AD,” said Professor Atzmon of the University of Haifa. This genetic finding correlates with the Druze community’s beliefs regarding their origin.
Traditionally, the Druze people believe that their community was founded in the 11th century AD as a new religious movement under the sixth caliph of the Fatimid Dynasty of Egypt. There are currently 1.5 million Druze around the world, residing mainly in Syria and Lebanon, with the remainder in Israel and Jordan. According to Druze tradition, marriages take place only within the Druze community.
An international team of researchers was formed to perform this current study, published in the European Journal of Human Genetics — Nature, which sought to examine whether the Druze people of today have a similar gene pool and if so, when that gene pool began to take shape. The head of the team, Prof. Atzmon of the University of Haifa’s Department of Human Biology and of the Department of Medicine and Genetics, the Albert Einstein College of Medicine, NY, together with Prof. Zidan, the director of the oncology department at Ziv Medical Center and of the Faculty of Medicine in the Galilee, Bar-Ilan University and Prof. Eitan Friedman of the Sackler School of Medicine, Tel Aviv University, were joined by Dr. Dan Ben-Avraham of the Department of Medicine and Genetics, Albert Einstein College of Medicine, NY, Dr. Shai Carmi of the Department of Computer Science, Columbia University, NY, and Dr. Taiseer Maray of the organization, Golan for Development.
The study included 120 participants from forty families. Twenty families were from the village of Beit Jan located in the Upper Galilee and twenty were from Majdal Shams, in the Golan Heights. The families were selected according to the origins of their extended families (clans), based on their family names and on information that was passed down orally from generation to generation. The mother, father and son of each family were genetically tested. All the families who participated in the study were from different clans so that the sample would be representative and it excluded first- or second-degree family relationships to any other participants in the study. These characteristics all significantly increased the study’s genetic accuracy. “In this study, we incorporated data that was published on the Druze of Lebanon, the Carmel Mountain region and various other populations in order to test the genetic structure of the Druze population relative to other populations,” said Prof. Zidan.
The results indicated that the Druze do indeed share a high genetic similarity that significantly distinguishes them from member of other groups and communities in the Middle East. When the researchers went back in time to discover when this genetic similarity began, they reached the 11th century AD, about 22-47 generations ago (there are differences of opinion over the duration of a generation). During this period a genetic “bottleneck” was formed, i.e., the genetic origin of many descendants came to an end, the community’s population decreased and the individuals in the population became more alike genetically. According to Prof. Atzmon, their research findings limit the ancestors of the Druze community to several hundred families, who founded the community in the 11th century AD. The researchers also found that there is no evidence of new genes entering the Druze gene pool over the last 1,000 years. In other words, no additional groups from the outside joined this community. In addition, the researchers found evidence of genetic differences between Druze populations from different regions: Lebanon, the Golan Hights, the Upper Galilee and the Carmel Mountain. This strengthens the evidence that marriages take place only within each clan.
When they went further back in time, the researchers discovered another interesting finding. It came to light that, 500 years prior to the beginning of the Druze religion, around the 6th century AD and at the time of the birth of Islam, a genetic group began to take shape that formed the genetic basis of the Druze community’s ancestors.According to this study, the Druze genome is largely similar to the genome of other Arab populations in the Middle East. They also found a few genetic elements in the Druze genome that originated from Europe, Central and South Asia (the Iran region) and Africa.
“Our next step is to try to identify the genetic component of common diseases in this sector using the traditional family structure in a study that will allow genetic decoding of regular genetic diseases and provide data on diseases that have a genetic basis, such as cancer and diabetes. We are also planning similar studies in the future of the Muslim and Christian populations in Israel,” Prof. Friedman concluded.
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European Journal of Human Genetics — Nature