“Previous genetic studies based upon blood group and serum markers suggested that Jewish groups originated in the Middle Eastern with greater genetic similarity between groups of Jewish populations,” says Harry Ostrer, MD, professor of pediatrics, pathology and medicine at NYU Langone Medical Center and senior author of the paper, published in the June 11, 2010, issue of The American Journal of Human Genetics. “We have shown that despite the fact that individuals from the Diaspora have distinctive features that are representative of each group’s genetic history, they also share a set of common genetic threads.”
Dr. Ostrer and colleagues performed a genome wide analysis of Iranian, Iraqi, Syrian, Italian, Turkish, Greek and Ashkenazi Jews and compared these results with non-Jewish groups. The researchers identified distinct Jewish population clusters that each exhibited a shared Middle Eastern ancestry, proximity to contemporary Middle Eastern populations and variables degrees of European and North African genetic intermingling. Yet, amid all of these differences, the Jewish groups were more related to each other than to the non-Jewish groups in the study and were more likely to share long threads of DNA.
The study also demonstrated that the history of Jewish people could be found in their genomes. The two major groups, Middle Eastern Jews and European Jews, were timed to have diverged from each other approximately 2500 years ago. Southern European populations show the greatest proximity to Ashkenazi, Sephardic and Italian Jews, reflecting the large-scale southern European conversion and admixture known to have occurred over 2,000 years ago during the formation of the European Jewry. An apparent North African ancestry component was also observed as was present in the Sephardic groups potentially reflecting gene flow from Moorish to Jewish populations in Spain from 711 to 1492. The structure of the genomes of Ashkenazi Jewish populations indicates a severe bottleneck followed by expansion during the 19th century when the Jewish population in western and eastern Europe increased about twice as fast as the non-Jewish population. This has been referred to as “the demographic miracle.” Within every Jewish group, there was a high degree of relatedness between any two of its members. For Ashkenazi Jews, the relatedness was similar to what one might observe for fifth cousins.
Dr. Ostrer noted, “The study supports the idea of a Jewish people linked by a shared genetic history. Yet the admixture with European people explains why so many European and Syrian Jews have blue eyes and blonde hair. “
Co-authors of the study include Gil Atzmon, Bernice Morrow and Edward Burns of Albert Einstein College of Medicine, Itsik Pe’er and Pier Francesco Palamara of Columbia University, Eitan Friedman of Chaim Sheba Medical Center in Israel as well as Christopher Velez, Li Hao, Alexander Pearlman and Carole Oddoux of NYU Langone Medical Center.
The study is the first from the Jewish HapMap Project, a joint endeavor of NYU School of Medicine and Albert Einstein College of Medicine of which the goal is to understand the structure of the genomes in the Jewish populations. The research was funded by the Lewis and Rachel Rudin Foundation, the Iranian-American Jewish Federation, the U.S.-Israel Bi-national Science Foundation and private donors.
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