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NSGC Presentation Highlights Importance of Carrier Testing in Jewish Individuals From Non-Ashkenazi Populations

PITTSBURGH (GenomeWeb) – Preliminary results from an effort known as the Jewish Genetic Disease Prevention Project suggest Jewish populations with non-Ashkenazi ancestry may benefit from carrier screening focused on a range of recessive conditions.

Speaking at the National Society of Genetic Counselors annual education meeting today, Stephanie Farner, a genetic counselor with the San Diego-based genetic testing company Progenity, described initial findings from an effort to screen Mizrahi, Sephardic, and Persian Jewish populations from multiple US cities.

The majority of Jewish Americans belong to the Ashkenazi Jewish population, which is found in Eastern Europe, Farner explained. But an estimated 5 percent or so of Jewish individuals in the US have ancestors from other Jewish populations, including the Sephardic population from the Mediterranean, Greece, and Turkey; the Mizrahi population, with ancestry from the Middle East; and Persian Jewish population, which is centered in Iran.

Whereas Ashkenazi Jewish individuals routinely participate in carrier screening tests for

Tay-Sachs disease, Canavan disease, cystic fibrosis, and other conditions, Farner noted, there are currently no clear guidelines regarding the types of carrier testing, if any, that should be performed in individuals from other Jewish populations.

Instead, recommendations for these individuals may depend on factors such as their country of origin, which may or may not include testing on recessive disease genes that the individuals might carry.

In an effort to more fully characterize the carrier conditions affecting Sephardic, Mizrahi, and Persian Jewish populations in the US, Farner and her co-authors used Progenity testing to assess the carrier status of individuals recruited to community events in 2014 in Los Angeles, Dallas, Seattle, and so on.

She and her colleagues reached out to these populations with the help of Jewish leaders and social media, inviting them to participate in a community testing event that involved on-site genetic counseling, informed consent, and a blood draw.

At the carrier testing events, screening was offered to adult individuals who intended to have children in the future. After speaking with a genetic counselor and providing informed consent, the individuals had blood drawn by a phlebotomist, which was tested for a wide range of recessive conditions at Progenity's CLIA-certified, CAP accredited lab.

So far, the researchers have found that more than one in every four individuals tested — some 27 percent — carry risky versions of genes associated with at least one of the conditions assessed. Another 2 percent tested positive for alleles associated with two of the diseases.

The most commonly detected disease alleles were those associated with risk of the X-linked recessive condition glucose-6-phosphate dehydrogenase deficiency (G6PD) — an anemia syndrome (sometimes called favism) in which red blood cells spontaneously self-destruct in response to oxidative stress.

Farner noted that one woman who tested positive for G6PD had been manifesting symptoms of the disease but did not know she was affected until test results were returned to her.

The next most commonly detected carriage in the Sephardic, Mizrahi, and Persian Jewish individuals was for alleles implicated in an episodic fever-and-inflammation disease called familial Mediterranean fever, though carriers for several other recessive conditions were identified as well.

Such results suggest that more widespread carrier screening may benefit Jewish Americans who do not belong to the Ashkenazi population or who have a mixed Jewish ancestry, Farner explained.