- Aug 19, 2003
: American Technion Society
http://www.sciencedaily.com/releases/20 ... 083446.htm
Nearly Half Of Ashkenazi Jews Descended From Four 'Founding Mothers'
Some 3.5 million or 40 percent of Ashkenazi Jews are descended from just four “founding mothers” who lived in Europe 1,000 years ago. The mothers were part of a small group who founded the Ashkenazi Jewish community, which was established in Europe as a result of migration from the Near East.
The studies that led to these findings were performed by Dr. Doron Behar as part of his doctoral thesis, and were done under the supervision of Prof. Karl Skorecki of the Rappaport Faculty of Medicine and Research Institute at the Technion-Israel Institute of Technology, and at the Rambam Medical Center in Haifa. Prof. Skorecki is best known for his 1997 discovery of genetic evidence indicating that the majority of modern-day Jewish priests (Kohanim) are descendants of a single common male ancestor, consistent with the Biblical high priest, Aaron.
Researchers from other universities around the world contributed to the study, which was published online January 11 by the “American Journal of Human Genetics” and will appear in print in a forthcoming issue of the Journal.
The researchers’ conclusions are based on detailed comparative analysis of DNA sequence variation in the mitochondrial DNA (mtDNA) region of the human genome. mtDNA is transmitted to descendants by the mother only.
The researchers found that the mtDNA of some 3.5 of the 8 million Ashkenazi Jews in the world can be traced back to only four women carrying distinct mtDNA of a type virtually absent in other populations. Non-Ashkenazi Jews also carry low frequencies of these distinct mtDNA types, providing evidence of shared maternal ancestry of Ashkenazi and non-Ashkenazi Jews. This is consistent with previous findings based on studies of the Y-chromosome, pointing to a similar pattern of shared paternal ancestry of global Jewish populations, originating in the Near East. The researchers concluded that the four founding mtDNA – likely of Middle Eastern origin – underwent a major overall expansion in Europe during the last millennium.
The Ashkenazi Jewish population has been the subject of numerous studies of human genetics because of the accumulation of some 20 recessive hereditary disorders that are concentrated in this population.
The human genome project has enabled mapping of human DNA sequence variation, which enables not only the prediction of certain genetic diseases, but also the identification of family and genealogical relationships (e.g. shared ancestries) among individuals. The human genome includes some 3 billion chemical letters, known as nucleotides – which comprise the sequence of nucleic acids in DNA in almost every cell of the human body.
Most of the human genome is diploid, containing representation of both parents. The Y-chromosome and mitochondria DNA are haploid, containing DNA transmitted from only one parent. Thus, the Y-chromosome provides information about paternal ancestry while mtDNA provides information about maternal ancestry. As a result, DNA sequence analyses of these two regions of the human genome are important tools in phylogenetics – the study of global populations through genetic analysis.
The discoveries of Dr. Behar, Prof. Skorecki and their research colleagues have significant implications beyond their inherent interest and relevance to human history; they are vital to understanding the mechanisms of genetic health and disease in human populations.
The Technion-Israel Institute of Technology is Israel's leading science and technology university. Home to the country’s winners of the Nobel Prize in science, it commands a worldwide reputation for its pioneering work in nanotechnology, computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine. The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society is the leading American organization supporting higher education in Israel, with 17 offices around the country.