Most persons of Jewish heritage in the United States trace their ancestry to Germany or Eastern Europe (Ashkenazi), the Mediterranean (Sephardic) or Iran/Persia and the Middle East (Mizrahi). In order to understand which diseases an individual should be screened for, it's important to understand their genetic heritage.
The majority of Jews in the United States trace their ancestry to Germany and Eastern Europe. These Jews are known as Ashkenazi, from the medieval Hebrew term for Germany. It is estimated at 90% of the Jews in the United States are Ashkenazi, most with ancestors who emigrated in the late 19th and early 20th century.
They share a common genetic heritage and risk from well-defined group of genetic diseases. Tay-Sachs Disease was the first disease identified and screened for in Ashkenazi Jews and is still the one most often known in the general public
At this point there are 19 genetic diseases common to Ashkenazi Jews for which preconception carrier screening is recommended, including cystic fibrosis (CF) and spinal muscular atrophy (SMA), for which carrier screening is recommended for all populations. Research shows that Ashkenazi Jews are generally aware of the concept of inherited genetic diseases, but often do not understand the need for preconception carrier screening, and rarely know the entire list of diseases for which they should be screened.
Individuals of Ashkenazi ancestry should note that screening for one of the diseases on the list, Gaucher disease, may reveal that the individual actually has the disease. For more information visit the Medline Plus article on Gaucher and the Gaucher Foundation.
Note: For the most sensitive and accurate carrier detection available for Tay-Sachs, the Canavan Foundation highly recommends either: 1) a combination of DNA and biochemical carrier screening (enzyme analysis), or 2) next generation sequencing of the HEXA (Tay-Sachs) gene. There may be different costs associated with these approaches, so it is best to consult with a genetic counselor before proceeding.
The two non-Ashkenazi Jewish populations in the United States are generally identified by the terms Sephardic and Mizrahi. Sephardic, from the Hebrew term for Spain, generally refers to the Jews who trace their heritage back to the expulsion of the Jews from Spain in 1492, at which point they emigrated to other points around the Mediterranean, including North Africa. Mizrahi, from the Hebrew terms for “East,” generally refers to Jews of Persian (Iranian) and Middle Eastern heritage.
The two terms are used somewhat imprecisely and often overlap when referring to country of origin, religious practice or genetic heritage. Persian Jews generally refer to themselves as such, while others who come from Middle Eastern countries may use the term Sephardic as a catch-all for non-Ashkenazi Jewish heritage and practice. In our materials, the JGDC utilizes the umbrella term Sephardic/Mizrahi to refer to non-Ashkenazi Jews and attempts to specify country or region of origin for each disease.
Due to the diverse genetic heritage of the Sephardic/Ashkenazi Jewish population, the smaller size of this group (estimated at only 10% of the Jews in the United States) and the fact that less research has been done, screening recommendations are still in a state of development. The Jewish Genetic Disease Consortium (JGDC) lists 16 diseases for which preconception screening should be considered, depending on country or region of origin, although no one individual would be screened for all 16.
Due to the rarity of some of the Sephardic/Mizrahi conditions, and the rapidly advancing state of research into these populations, tests are not as widely available and fewer genetic counselors are training to work with these populations. Given the concentration of the Persian Jewish emigrant populations on the North Shore of Long Island in Los Angeles, the genetics program at North Shore LIJ in Manhasset and Cedars-Sinai in Los Angeles can be useful resources for information and testing.
American Jews generally identify with one of four movements: Reform, Reconstructionist, Conservative and Orthodox. Religious practice and engagement with the mainstream population varies among the four, with Orthodox offering more guidelines and structures for daily living. Orthodox Judaism itself has a wide spectrum of practice, from those Jews referred to as Modern Orthodox to the more observant Haredi or Ultra-Orthodox, who tend to live in their own communities.
The more observant Orthodox community has a genetic screening program called Dor Yeshorim (Upright Generation), based in Brooklyn. Young adults are screened before considering marriage, and carrier couples are discouraged from marrying. They perform screening for 9 Ashkenazi diseases unless additional tests are requested and results are not released to the patient. Both men and women are screened anonymously at Dor Yeshorim and their results are stored until the time of the match making process.
Jewish family heritage, not religious practice, is the risk factor for inherited genetic disease. It is quite possible that an individual who does not identify as Jewish in a religious sense is Jewish in terms of genetic heritage. What's important is the geographic and religious identification of parents and grandparents, not synagogue membership.
All streams of Judaism in the United States have given their support to preconception genetic screening, starting with the Tay-Sachs screening programs in the 1970s.