A first-of-its-kind genetic study of the Druse community in Israel and abroad, has found that they formed around the 11th century CE and has confirmed that they traditionally marry only within their extended families.The genetic study confirmed the history of the Druse community going back a millennium. Since the 11th century, there has been no genetic impact of other ethnic groups on the community. “Our findings correlate with the Druse community’s beliefs regarding their origin,” Prof. Gil Atzmon commented.Traditionally, the Druse people believe that their community was founded 1,000 years ago as a new religious movement under Egypt’s sixth caliph of the Fatimid Dynasty.There are currently 1.5 million Druse around the world who live mainly in Syria and Lebanon, with the rest in Israel and Jordan. According to Druse tradition, marriages take place only within the clans.An international team of researchers was formed to carry out the study, just published in the European Journal of Human Genetics – Nature. The team sought to examine whether the Druse of today have a similar gene pool and if so, when it began to take shape.The research was led by Atzmon, professor of human biology at the University of Haifa, with oncology Prof. Jamal Zidan of Bar-Ilan University’s Faculty of Medicine in the Galilee in Safed and Prof. Eitan Friedman of Tel Aviv University’s Sackler Faculty of Medicine. The team also included Dr. Dan Ben-Avraham of the department of medicine and genetics at New York’s Albert Einstein College of Medicine; Dr. Shai Carmi of the computer science department at New York’s Columbia University; and Dr.Taiseer Maray of the Golan for Development organization.The study included 120 participants from 40 Druse families; half of whom were from the village of Beit Jann in the Upper Galilee and the rest from Majdal Shams on the Golan Heights.They were selected according to the origins of clans, based on their family names and information that had been 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 Druse of Lebanon, the Carmel Mountain region and various other populations to test the genetic structure of the Druse population relative to other populations,” said Zidan.The results indicated that the Druse do indeed share a high genetic similarity that significantly distinguishes them from members of other groups and communities in the Middle East. Researchers discovered that this genetic similarity began in the 11th century, about 22 to 47 generations ago (there are differences of opinion over the duration of a generation).During this period, a genetic “bottleneck” was formed; the genetic origin of many descendants came to an end; the community’s population decreased and the individuals in the population became genetically more alike. According to Atzmon, their research findings limit the ancestors of the Druse community to several hundred families who founded the community 1,000 years ago.No additional groups from the outside joined this community since then. In addition, the researchers found evidence of genetic differences among Druse populations from Lebanon, the Golan Heights, the Upper Galilee and the Carmel Mountain area. This strengthened the evidence that marriages have taken place only within each extended family.The researchers discovered that 500 years before the beginning of the Druse religion, around the 6th century CE and at the time of the birth of Islam, a genetic group began to take shape that formed the genetic basis of the Druse community’s ancestors.The Druse genome was found to be largely similar to the genome of other Arab populations in the Middle East. They also found a few genetic elements in the Druse 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,” Friedman said.