'Previous genetic studies of blood group and serum markers suggested that Jewish groups had Middle Eastern origin with greater genetic similarity between paired Jewish populations,' says senior study author, Dr. 'More recent studies of Y chromosomal and mitochondrial DNA have pointed to founder effects of both Middle Eastern and local origin, yet, the issue of how to characterize Jewish people as mere coreligionists or as genetic isolates that may be closely or loosely related remained unresolved. Yet the genomes of the Jewish Diaspora groups have distinctive features that are representative of each group's genetic history.' says Dr. 'Our study demonstrated that the studied Jewish populations represent a series of geographical isolates or clusters with genetic threads that weave them together,' added Dr. The researchers identified distinct Jewish population clusters that each exhibited a shared Middle Eastern ancestry, proximity to contemporary Middle Eastern populations and variable degrees of European and North African genetic intermingling. 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. Ostrer noted, 'The study supports the idea of a Jewish people linked by a shared genetic history."Abraham's Children in the Genome Era: Major Jewish Diaspora Populations Comprise Distinct Genetic Clusters with Shared Middle Eastern Ancestry." The American Journal of Human Genetics 86:6 (June 3, 2010): pages 850-859.
Additionally, we applied extended haplotype tests to determine whether positive selection can account for the level of AJ-prevalent diseases.
We identified genomic regions under selection that account for lactose and alcohol tolerance, and although we found evidence for positive selection at some AJ-prevalent disease loci, the higher incidence of the majority of these diseases is likely the result of genetic drift following a bottleneck.
In addition, analyses of disease-related genes of higher prevalence in the Ashkenazi Jewish population indicate that only a minority of traits show signs of positive selection, suggesting that most have arisen through random genetic drift.
[...] 'We were surprised to find evidence that Ashkenazi Jews have higher heterozygosity than Europeans, contradicting the widely-held presumption that they have been a largely isolated group,' says first author Steven Bray, Ph D, a postdoctoral fellow in Warren's laboratory.
Our analysis indeed revealed higher European admixture than predicted from previous Y-chromosome analyses.
Moreover, we also show that admixture directly correlates with high LD, suggesting that admixture has increased both genetic diversity and LD in the AJ population.
Thus, this study demonstrates that European/Syrian and Middle Eastern Jews represent a series of geographical isolates or clusters woven together by shared IBD genetic threads." "The genetic, cultural and religious traditions of contemporary Jewish people originated in the Middle East over three thousand years ago.
Since that time, Jewish communities have migrated from the Middle East into Europe, North Africa and across the world. This study shows that although Jewish people experienced genetic mixing with surrounding populations, they retained a genetic coherence along with a religious one.
Researchers in New York and Tel Aviv conducted a genome-wide analysis on 237 individuals from seven well-established Jewish communities around the world, hailing from Iran, Iraq, Italy, Greece, Turkey, Syria and eastern Europe.