Title: Exploring the genetic diversity of the Sephardic remnants in Northeast Portugal from autosomal data
Abstract: The word “Jew” derives from Judah, one of the twelve Tribes of Israel. It can define a follower of the Jewish faith, a descendent of a Jewish family or simply a person belonging to a certain ethnic group. There are essentially two phenomena that are important to understand in order to better know this people: the Diaspora, and the Crypto-Judaism, being the latter defined as the secret adherence to Judaism while publicly professing another faith. In Portugal, the oldest archeological evidence found of Jewish presence dates back to the 4 century. From then to the 19 century, the Jewish communities in Portugal experienced tolerant periods, when the population proliferated, as well as others periods marked by restrictive measures and persecutions against Jews. However, in Braganca, Northeast Portugal, there is still a small community that preserves its culture. Geneticists have been studying Jewish populations since the turn of the 20 century, in order to try to unravel what must be a complex system of interrelations among Jewish communities and non-Jewish hosts populations, but there is still a huge gap regarding the genetic characterization of Iberian Judaic populations, especially concerning autosomal markers. Our aims are to offset this limitation and to increase the current knowledge about the origin and demographic history of these populations, complementing the studies conducted by Nogueiro and coworkers (2010) and Teixeira and coworkers (2011), based on mtDNA and ChrY lineage markers. We also pretend to seek for differences between this population, others Jewish population, and neighbor non-Jewish local populations. The results obtained with lineage markers concur to show that the communities scattered over the Braganca district have succeeded in maintaining a high level of genetic diversity with a clear root in the Middle East. These findings are extremely surprising, as they show exactly the opposite of what is expected in isolated, small sized populations, namely a deep genetic diversity loss. With autosomal microsatellites markers, we saw that regarding the major standard diversity indices, this community presented itself very similar to its non-Jewish Portuguese hosts (Braganca and Miranda), to other populations from Portugal, and to other Jewish communities from different Diaspora countries. With ancestry informative InDels, the behavior of this population is closer to Europe than to any other continent. Once the lineage markers have shown a substructure within this community, we also wanted to prove that result with autosomal markers. However, an absence of sub-structuration was found, contrarily to what would be expected. FCUP Exploring the genetic diversity of the Sephardic remnants in Northeast Portugal from autosomal data V When we compared our population of interest with its long-term non-Jewish hosts, through several statistical analyses, we concluded that there are no differences between the Jewish community and its neighbors. The next step was to understand the relation between the Portuguese Jewish community and other Jewish populations from Diaspora countries. Nevertheless, an absence of differentiation between populations was also the result. At this point, we already knew that our population of interest present itself as a normal outbreeding population, without within substructure, and very genetically close and similar to non-Jewish Portuguese and other Jewish populations. Then, we wanted to understand its relation with other worldwide populations, especially with European and Middle Eastern ones, under the light of slow mutating markers. Although the distinction between Europe and Middle East was not very clear, the Braganca Jewish population presented a genetic behavior much more similar to Europe than to Middle East. Finally, it is important to note that, although none of our autosomal analyses was able to detect any kind of structure, we know that this population is not that homogenous, from previous results with lineage markers. The solution could be an increase of the number and informativeness of the markers. So, the use of genome-wide microsatellite markers would be of great importance in the understanding and evaluation of the genetic relationships involving Jewish communities.
Publication Year: 2013
Publication Date: 2013-12-06
Language: en
Type: dissertation
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