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Analyses of mitochondrial DNA suggest Ashkenazi lineages may originate in Europe

A recent study, published on October 8, 2013 in Nature Communications, indicates that maternal Jewish lineages may have a European origin. Sequencing data of Ashkenazi mitochondrial DNA suggests that maternal lineages originated within Mediterranean Europe rather than brought from the Near East or Caucasus.

What is mitochondrial DNA?
What is mitochondrial DNA?
Anita P. Kuan, Source: NIH
Segment of DNA
Segment of DNA
National Human Genome Research Institute

There are approximately 116,000 Jewish people in Connecticut (2012 data; ~6.7 million in the U.S.). A majority of Jews today are descended from Ashkenazi Jews (~80%). However, the origins of Ashkenazi Jews remain highly controversial.

Like Judaism, mitochondrial DNA is passed along the maternal line (along the mother’s side). Thus far, reconstructing relationships using genetic information has suggested contradictory conclusions. While some point to a primarily Near Eastern ancestry – a region that includes Israel/Palestine, Lebanon, Syria and Jordan – others suggest a largely Caucasian ancestry.

This recent study sequenced 74 mitochondrial genomes and analyzed over 3500 mitochondrial genomes from across Europe, the Caucasus, and the Near East to provide a detailed reconstruction of Ashkenazi genealogical history. The study shows that over 80% of the variation in Ashkenazi mitochondrial DNA, also known as mtDNA, has ancestry in prehistoric Europe, rather than the Near East or Caucasus. This implies that female Ashkenazi Jews may have been assimilated in Europe around 2,000 years ago.

Analysis of whole mitochondrial DNA genomes gives a high resolution and may provide a detailed reconstruction of the genealogical history of Ashkenazi women. These results are an important step in resolving some of the conflict over the origins of Ashkenazi Jews – just another example of the far-reaching effects of genetics.

Studies show Ashkenazi Jews are genetically unique and distinct from the overall European population. This genetic isolation has implications on health. Genealogy and heritage can be useful for health reasons. For example, certain genetic disorders occur more often in people of Ashkenazi Jewish heritage than in the general population (e.g., approximately one out of four people of Ashkenazi heritage is a carrier of a rare genetic condition such as Gaucher disease, cystic fibrosis, Tay-Sachs disease, familial dysautonomia, or Canavan disease). And Ashkenazi Jewish ancestry increases the chances of having a BRCA gene mutation (the mutation associated with increased risk of breast and ovarian cancer). Knowing a person’s genealogy and ancestry may help in determining the risk of various diseases and allow for more informed medical decisions.

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