How Do Sephardic Jews Figure Into The Genetic Equation?
When Hispanic women in Colorado?s San Luis Valley were shown to carry a high frequency of the Ashkenazic breast-cancer gene, some genetic experts began to wonder.
Subsequent investigations showed that the women in question were likely the descendents of conversos fleeing the Inquisition, who settled in the region late in the 16th century.
A number of recent scientific studies have shown that illnesses long thought to occur only among Ashkenazic Jews can be found among Sephardim as well. Such findings, experts say, may alter not only how individual genetic disorders are viewed but also the very notion of the ?Jewish genetic disease.?
A recent Tel Aviv University study, along with others conducted in Colorado and Montreal, has shown that the BRCA1 ?Ashkenazic? breast-cancer mutation began to appear before the Jewish people?s major exiles and diasporas. The identical mutation appears in Ashkenazim and Sephardim, indicating an ancient common founder.
The marker has been found in Mizrahim (Jews from North Africa and the Middle East) and among Hispanics in Los Angeles and other cities. It also appears in Spain, Chile, Turkey, Yemen, Iraq, Morocco, Greece, Iran, Pakistan and Egypt ? all lands with histories of Jewish migration.
And the breast-cancer mutation is not alone among genetic illnesses previously thought to be unique to Ashkenazic Jews.
Bloom?s syndrome has been found in Chile, Costa Rica, Mexico, El Salvador and the southwestern United States, although those who tested positive have denied Jewish ancestry. In a heavily Catholic country, such a response may still be a form of protection against persecution.
Because 90% of American Jews are of Ashkenazic descent, it is safe to assume that non-Ashkenazic populations have been underrepresented in studies, according to Dr. Harry Ostrer, the director of the human genetics program at the NYU Medical Center.
?It?s an important question that should be asked,? said Dr. Susan J. Gross, a co-director of the division of reproductive genetics at the Montefiore Medical Center, in New York. ?Looking at this issue beyond the Ashkenazi community is of vital importance, and is not merely an academic exercise. Advancing our knowledge in this area can be of major significance to a much broader spectrum of Jewish women beyond this particular group.?
Authors of a study on Parkinson?s disease among Ashkenazim readily admit that the number of non-Ashkenazim they have studied is extremely small.
Dr. Laurie Ozelius and Dr. Susan Bressman, both of Yeshiva?s Albert Einstein College of Medicine, said that they want to obtain control samples from non-Ashkenazic groups.
?Our study reported a higher frequency in Ashkenazim because we had more Ashkenazi patients. North Africans also had a high frequency, but except for one Sephardic individual there were few non-Ashkenazim tested.?
The two suspect the disorder to be just as common in non-Ashkenazi Jewish populations as it is among Ashkenazim. Being able to see a few hundred Sephardic and Mizrahi individuals, they said, could ?change the entire picture.?
?We won?t know until we get samples,? Bressman said. ?We need to get many samples and look at many diseases with diverse ancestry in mind.?
In their small sample, Ozelius said, she found cases in Spain, Portugal, Italy ? all seemingly following Jewish migration paths.
?By looking at inbred or isolated populations, we can find new genes and understand new diseases,? Bressman said. ?Whether common genes are shared or not, this is an entire group of diverse Jews which needs to be investigated.?
In Boston, Dr. Daniel M. Laby, an assistant clinical professor of ophthalmology at Harvard Medical School, brings more than just a physician?s training to the table. Laby is also a genealogist with 13th-century documents on his Sephardic family, Laby de la Cavalleria.
?If you are going to talk to people, especially Jews, about breast cancer, you also need to be up on background and history,? he said, adding that it isn?t correct to say that a gene is only Ashkenazic when it is Jewish. ?It?s bordering on malpractice not to inform those who may be of non-Ashkenazi origin.?
In Laby?s view, a thorough knowledge of Jewish history and immigration should be required of genetic counselors.
Further complicating matters is the fact that that some who today identify as Ashkenazim may really have been Sephardim who migrated to Eastern Europe 500 years ago.
Jewish genealogists and academic researchers are discovering Sephardim among Eastern European ancestors.
Today, researchers aware of such factors are actively looking for ways to involve non-Ashkenazi Jewish populations in various studies.
?We really need both genealogy and DNA on all these communities ? it is imperative,? Bressman said. ?Genealogists and geneticists must work together and this will result in a wealth of science.?
Schelly Talalay Dardashti, a native New Yorker now living in Israel, served for a number of years as the Jewish genealogy columnist for The Jerusalem Post.