MONTREAL — The Canadian-born doctor who made international headlines with his discoveries that a large proportion of today’s Jews share common genetic markers warns that blood should not be the primary definition of Jewish identity.
Dr. Karl Skorecki
Dr. Karl Skorecki, a Torontonian who made aliyah in 1995, said Jews are a community because of their faith, culture and history, not biology. Jewishness should be rooted in the “metaphysical, not the physical,” he said while in Montreal recently.
He also emphasized that at the level of their DNA code, all human beings are 99.9 per cent identical.
In 1997, Skorecki found DNA evidence that the majority of modern-day kohanim, or members of the Jewish priestly caste, are descended from a single common male ancestor, although he hasn’t proven that it’s the biblical Aaron, as Jewish tradition holds.
In 2005, he showed that about 40 per cent of today’s Ashkenazim are descended from four “founding mothers.”
In both instances, these common markers are associated with the branch of the human family originating in the Near East about 3,000 years ago, which has led Skorecki to conclude that most of the Diaspora communities in the world today can trace their lineage back to the land of the Bible.
This makes Ashkenazi Jews closer cousins to Syrians, Kurds and Palestinians than to non-Jewish Europeans, he said.
This research has allowed Skorecki to blend his scientific vocation with his devotion to religious tradition. He says it validates the “population genetics” approach to medicine, and bears out much of Jewish teaching.
Skorecki spoke at a gathering organized by former Jewish General Hospital executive director Henri Elbaz, who is trying to make Israel’s Rambam Health Care Campus better known in Montreal.
Skorecki is director of medical and research development at the Haifa-based hospital, as well as professor of medicine and director of the Rappaport Research Institute at the Technion – Israel Institute of Technology.
Skorecki, the only son of Holocaust survivors, was born and raised in Toronto, and educated at the University of Toronto and Harvard university. Although a kohen himself, he said he has never had his DNA tested.
He was associated with Toronto’s Hospital for Sick Children, specializing in nephrology, before moving to Israel.
He became interested in genetic research because of the association between heredity and some types of kidney disease.
The markers Skorecki studied in his Jewish genetic research are mutations, or errors, in DNA replication. Ninety-five per cent of these mutations have no effect on health, appearance or behaviour, but they are a useful tool in tracing ancestry.
To look into paternal lineage, markers on the Y chromosomes, which are passed from fathers to sons, are studied. For maternal lineage, mitochondrial DNA, which only women can pass to their male or female children, is scrutinized. Samples were obtained by a simple swiping of the inside of the cheek.
The sequences of these markers were compared to samples from European non-Jews. Most of the non-Jews were found to have their roots in Eurasia.
The sharing of genetic material among Jews is not limited to the Ashkenazi community. Skorecki also found that the Lemba ethnic group of southern Africa, which claims descent from the Jewish people, have some of the same markers, even though they belong to a different race.
While African-Americans have a high incidence of kidney disease, he said Ethiopian Jews have a very low incidence, because they’re genetically different, he said.
Similarly, the descendants of Jews in Kaifeng, China, and in India were also found to have a genetic makeup suggesting Near Eastern ancestry, he said. In all, Skorecki and his team have sampled thousands of Jews, or those who claim Jewish roots, in 18 communities worldwide.
About 20 per cent of people in the Iberian Peninsula have the markers of Jewish patrilineage, which corroborates historical evidence that many Jews were forced to convert or hide their Jewishness in Spain and Portugal. With the proliferation of easy DNA testing, people with Jewish ancestry are also showing up in New Mexico and South America, he said.
Skorecki, who is observant, said the finding validates the traditional history of Askenazi Jews, who went into exile 2,000 years ago, making their way to Europe.
“This has an important impact in genetic counseling and guides the way we do research and design therapies,” he said.
For example, the genetic disease cystic fibrosis is associated with 1,300 mutations in the general population. But among 95 per cent of Ashkenazim with CF, only six of those mutations are present.
The two notable exceptions are some Dutch Jewish males. “Holland is more liberal. Jews might have more readily accepted the children of mixed marriages,” Skorecki said.
The other anomaly are the Levites, who had a tradition of paternal lineage, living in the areas of the Caspian and Black Seas. Their ancestors may have been converts, such as the Turkic Khazar, or rape is another explanation, he said.
While this information has political implications, Skorecki insisted his primary interest is the value of this tool in better understanding the role of genetics in disease. Genetic makeup may predispose one to disease or have protective effect. It also helps in determining what the best treatment might be for each person, he said.
