Study completes genetic map of N. African Jews

Until now, how N. African Jews are related to other Jewish groups, non-Jewish neighbors had not been well defined.

By
August 7, 2012 07:26
Jews pray in a Tunisian synagogue [file]

Jews pray in a Tunisian synagogue 370 (R). (photo credit: Anis Mili / Reuters)

 
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A just-published, “definitive” study of Jews of North African origin has set their place on the genetic map of the Jewish Diasporas. This completes research of contemporary Jewish populations following previous work on Ashkenazim, Sephardim and Mizrahi Jews who originated in Europe and the Middle East.

The study – led by Prof. Harry Ostrer of the departments of pathology, genetics and pediatrics at the Albert Einstein College of Medicine at New York’s Yeshiva University, was just published online in the Proceedings of the US National Academy of Sciences.

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The researchers analyzed the genetic make-up of 509 Jews from 15 populations compared with genetic data on 114 individuals from seven North African non-Jewish populations.

North African Jews are the second largest Jewish Diaspora group. Until now, how they are related to each other, to other Diaspora groups and to their non-Jewish North African neighbors had not been well defined.

The study also included members of Jewish communities in Ethiopia, Yemen and Georgia.

The findings support the historical record of Middle Eastern Jews settling in North Africa during classical antiquity, converting non-Jews to Judaism and marrying local populations, thereby forming distinct populations that stayed largely intact for more than two millennia.

“Our new findings define North African Jews, complete the overall population structure for the various groups of the Jewish Diaspora and enhance the case for a biological basis for Jewishness,” said Ostrer, an Einstein physician who is director of genetic and genomic testing for the division of clinical pathology at nearby Montefiore Medical Center. Ostrer noted that obtaining a comprehensive genetic fingerprint of various Jewish subpopulations can help reveal genetic links to heart disease, cancer, diabetes and other common diseases.



In a previous genetic analysis, the researchers showed that modern-day Sephardi (Greek and Turkish), Ashkenazi (Eastern European) and Mizrahi (Iranian, Iraqi and Syrian) Jews originating in Europe and the Middle East are more related to each other than to their contemporary non-Jewish neighbors, with each group forming its own cluster within the larger Jewish population.

In addition, each group showed Middle-Eastern ancestry and varying degrees of mixing with surrounding populations.

Two of the major Jewish populations – Middle Eastern and European Jews – were found in the Einstein study to have diverged from each other about 2,500 years ago.

North African Jews exhibited a high degree of endogamy – a term that refers to marriage within their own religious and cultural group – in accordance with their community’s custom.

Two major subgroups within this overall population were identified – Moroccan/Algerian Jews and Djerban (Tunisian)/Libyan Jews. The two subgroups varied in their degree of European mixture, with Moroccan/Algerian Jews tending to be more related to Europeans, which most likely resulted from the expulsion of Sephardi Jews from Spain during the Inquisition starting in 1492.

Ethiopian and Yemenite Jewish populations also formed distinctive genetically linked clusters, as did Georgian Jews.

The Jerusalem Post asked for comments on the paper from Prof. Karl Skorecki, a leading genetics researcher and nephrologist – kidney care specialist –at Haifa’s Rambam Medical Center who has done pathfinding work on the ancient links of the Priestly Tribe and Y chromosomes.

“This Einstein-led research is definitive,” said Skorecki, a modern- Orthodox Jew who said he is closely familiar with the paper and the “superb researchers” involved in it.

“One of its great strengths is the interdisciplinary collaboration, including among other experts such as historians. The context of historical expertise greatly enhances the ability to understand and draw inferences from the genetic analysis,” Skorecki said.

“This paper continues the team’s excellent work in the past few years on DNA markers across the entire genome. The second largest Diaspora community, from North Africa, was missing. The various Jewish communities share with each other and have a great deal of overlap.”

Skorecki said he did not work with the team this time, but has before. “A monopoly is not good,” he said. “It’s better for many different groups from different parts of the world to work independently and even competitively perform similar research, as it adds to credibility and confidence.”

Jews who were forced out of Spain and Portugal in the late 15th century moved eastward to Bulgaria, Turkey and Saloniki, but also to Morocco in North Africa.

“This is clear. There is very interesting genetic consistency and a confirmation of history that we have obtained from archival historical records. Using genetics can also be a historical tool,” the Rambam expert said.

“When one looks for geneticbased predisposition to diseases, it’s important to know to what other population the given group is genetically related, in this case, the non-Jews in the same area. The new findings show that there was not much Jewish admixture with the local non-Jewish population in North Africa. Compared to the variation of the worldwide population, Jewish communities were quite different. They mostly married among themselves, with not enough mixing with the non- Jewish group to make it possible to separate the DNA.

One can see that there is shared Jewish ancestry of Near East origin among Ashkenazim and other Jews who had been separated for thousands of years.”

Skorecki,  who is also at the Technion-Israel Institute of Technology in Haifa, noted that new studies, such as a major one a few weeks ago from University College London researchers in the American Journal of Human Genetics, have shown that the general population in Ethiopia has the most diverse structure in the world.

“There was a great deal of diversification, so it’s a great place to study genetics,” said Skorecki.

“Many researchers,” he continued, “believe that humans originated in more than one place, but contemporary humans probably descend mostly from humans from northeast Africa, such as Ethiopia.

“I, like them, think that they were dark skinned, and as they moved, their skin color evolved to adapt to their environment,” said Skorecki.

His own research group at Rambam and others are currently involved in studying the whole genome of three billion letters.

Now Jewish samples are being studied for whole genome sequences – every single letter of the bases making up pairs in the DNA – which will provide even more insight on human health.

Skorecki believes the non-Jewish academic world is interested in Jewish genetics as scholars of history. Probably, the Jewish connection to the Bible also interests them, he said.

There is similar international interest in the people of Iceland and their diseases, just as there is in the Druse who often marry their first cousins, and Ashkenazi Jews who married among themselves for many centuries.

“One can understand their genetic structure and then learn a lot about health. Everything is headed towards whole genome studies,” said Skorecki.

A “personalized medicine initiative” based at the Weizmann Institute of Science in Rehovot and coordinated by Nobel Prize laureate Prof. Aaron Ciechanover, also of the Technion, is using modern technologies to get samples and understand genomes and proteins,” said the Rambam researcher.

Having two adult children who married Sephardi Jews, Skorecki said there is currently a “|window of opportunity” to do Jewish genetic research as Jewish/non-Jewish and Sephardi/ Ashkenazi intermarriage occurs. Assimilation in the US is high, but “in Israel, we welcome the coming together of descendants of separate Jewish communities and their marriage in Israel. Scientists in my grandchildren’s generation will say they are just Jews.”

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