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  • Sephardic mtdna

    Here's a link to new article of interest http://www.nature.com/doifinder/10.1038/ejhg.2011.200


    here's a summary of the paper linked to above

    The study discovered that there are a couple of variants/mutations in mitochondrial DNA that appear to be found only in people who are Sephardic or have a high suspicion of Sephardic ancestry. Recall that mitochondrial DNA is inherited only from one’s mother, so it’s become an indispensable tool for tracing maternal lineage back hundreds, sometimes thousands, of years. The people with high suspicion of Sephardic ancestry includes individuals from regions of northern Mexico and southwest USA that are known for crypt-Jewish settlement. These are very rare genetic variants, so the majority of Sephardim will NOT have them.

    Because the variant is so rare, the study also looked at the genetic group from which these variants derive. Here it was found that while this bigger genetic group is widespread geographically, it is more prevalent in Saudi Arabia, Egypt, and Italy than it is in Spain. In addition, Sephardim from Turkey and Bulgaria show this genetic pattern in numbers that are closer to these three regions than to Spain. This suggests that while Spain hosted Sephardim for 1500 years, the genetics are closer to regions in the Middle East and Italy than to host Spain. The geographic distribution suggested a migration path from the Middle East with a stop in Italy and on to Iberia and then into Western Europe. Since this migration path characterizes both Jewish and non-Jewish groups at various points in history, the work at present cannot prove that the Sephardic signature DNA is original Jewish DNA from exilers seeking asylum following destruction of the first temples by Romans or Babylonians. It is nonetheless exciting to tie DNA with a known historical migration path that is likely close to 2000 or more years old, something that is not always possible with DNA analyses.

    The work also theoretically briefly considers Sephardim and Ashkenazim on the so called issue of “founder effects” which address how many distinct individuals - in this case mothers- were responsible for the present day population in a community. A large or pronounced founder effect is said to occur if very few individuals were responsible for a large proportion of the current DNA in that population. It has been reported that Ashkenazim have a more pronounced founder effect than Sephardim. This certainly would make sense historically since there were more Sephardim than Ashkenazim until recently and Sephardim brought with them to new locations all their genetic variability when exiled from Iberia in the late 15th century. However, current comparisons erroneously combine all Ashkenazi communities together while keeping Sephardic communities separate – a comparison of apples and oranges. The bottom line is that at present this issue of founder effects has not been resolved. We do currently know limited things, such as descendents of the Sephardic community of Turkey have a less pronounced founder effect and greater genetic variability than descendents of the Ashkenazi community of Poland.

    Finally, another part of the data analyzed gets technical. The couple of rare variants in DNA mentioned above come from a part of the mitochondrial DNA known as the “control region”. This is the part that accumulates surviving mutations in the greatest numbers because these control regions do not typically code for anything important. Control regions have been tested the most, with at least 250,000 individuals tested worldwide that are available for searching, as was done in the present research. But recently, testing of the remaining regions of the mitochondrial DNA, from the “coding regions” is becoming more frequent. The coding regions do code important information and can have medical as well as other implications. Analysis of one Sephardic sequence from Salonica Turkey/Greece with the Sephardic signature of interest (based on control region mutations) was found to have a couple of further variants in the coding regions. Unlike the variants from control regions which were not remarked on before, these coding region variants are shared with others already in the scientific literature (and come from individuals who do not have the Sephardic control region mutations). These coding region mutations will eventually provide an important link of at least some of Sephardim with the rest of the world. It is very premature to speculate, but I suspect the origins of this broader more prevalent and widespread group may actually also be Jewish, even in those who neither know nor suspect this origin, but it will take a lot of work to prove this. If nothing else, it shows that the Sephardic signature individuals share a common maternal ancestor, anywhere from 500 to 16,000 years ago, with these other individuals.

    For those interested in details, the defining control region mutations for the Sephardic signature are the presence of both 16114T and 16192T in mitochondrial subhaplogroup T2e.

  • #2
    Very interesting. Thanks for posting this.

    I'm T2e4, with Italian ancestry, but I don't have either the control or coding region mutations that this study regards as an indicator of Sephardic ancestry. Reading the abstract that you linked to, I see that they used results from 8 databases. I wonder if they used the results from the T FGS project of which I'm a member.

    I find these quotes particularly interesting: "Search of the motif in 250 000 control region records across 8 databases, comparison of frequencies of T subhaplogroups (T1, T2b, T2c, T2e, T4, T*) across 11 diverse populations, creation of a phylogenic median-joining network from public T2e control region entries, and analysis of one Sephardic mitochondrial full genomic sequence with the motif.... Coding region mutations of 2308G and 14499T may locate the Sephardic signature within T2e, but additional samples and reworking of current T2e phylogenetic branch structure is needed." (bolding is mine) Do you have the full study? I'd like to their median-joining network diagram.

    I hope this leads to a better resolution of T2e and its subclades in the next revision of the mtDNA tree at www.phylotree.org

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    • #3
      I sent the link to David Pike, the administrator of the T FGS Project. He was not aware of the study.

      He was able to get a copy, which he provided to me, and saw that the T FGS Project was cited in the bibliography. The project's results were among those used for the study.

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      • #4
        hi mike - check your PM

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        • #5
          Originally posted by MMaddi View Post
          He was able to get a copy, which he provided to me, and saw that the T FGS Project was cited in the bibliography. The project's results were among those used for the study.
          That is awesome! It's nice they're giving it recognition. I bet even more academics troll the data in the various DNA projects, but without any acknowledgement.

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          • #6
            Any information on T2g as Sephardic? I know I have read that T2g was among the "Founding Mothers of Jews in Iran". Somehow my line got to Brittany, France.

            Thank, Miles Kehoe

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