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Wading Into the Gene Pool
At a recent conference on "Our Heritage and Our Health: The Importance of Being Informed/Understanding Jewish Genetic Diseases," Gary Frohlich, a leading New York trained and now California-based genetic counselor, opened by pronouncing that genetic diseases don't discriminate.
"Ashkenazi Jewish genetic diseases are not sex limited; that is, males and females are affected equally. When speaking about genetic diseases, we're talking about single gene disorders, not chromosomal abnormalities," Frohlich said, addressing a group gathered for the conference at the Jewish Community Services Building in Center City.
Providing an historical perspective, he noted that the Jewish experience with biological mutation dates back to the dispersion of Jews following the destruction of the Temples in Jerusalem. When the fleeing Jews established themselves in new lands, they did so with a reduced genetic component from the original population.
The discussion turned to what it means to be at risk for recessive genetic disorders that have their roots in such forced escapes in history, and the frequency with which they occur. "We're referring to a single changed gene that no longer functions correctly," explained Frohlich.
"You must have two parents with a changed gene to have an affected child, but you don't have to manifest a genetic disease to be a carrier."
Building upon this discussion, conference speaker Dr. Adele Schneider talked of the necessity for screening. "There are now 19 genetic diseases we can screen for. We need to make this a priority that is really embraced by the community," as Jews did when screening for Tay-Sachs became available, she said.
Schneider, director of clinical genetics at Einstein Medical Network and medical director of the Victor Centers for the Prevention of Jewish Genetic Diseases at Einstein, added: "One in four Ashkenazi Jews is a carrier of one of these 19 genetic diseases. When two carriers of a gene mutation for the same disorder have children, there is a 25 percent chance of having an affected child with each pregnancy.
"There are only two ways to find out if you're a carrier: have a screening test, or give birth to an affected child," Schneider stated.
While being a carrier is not life threatening, screening should ideally occur prior to pregnancy. "Carrier screening is available for all the diseases on the Jewish panel with a simple blood test," said Schneider.
Because some of these diseases may be severe and result in the early death of a child, Schneider recommended that all Ashkenazi Jews with one Jewish grandparent should be screened, even if they married a non-Jew.
Schneider cited the grass-roots efforts of the 1970s, when the devastating and fatal Tay-Sachs disease came to the forefront of the Jewish community's attention. Since screening for that disease 40 years ago, "the number of Jewish babies born with Tay-Sachs has decreased by more than 90 percent," Schneider reported.
While it is well known that each of these genetic disorders can be devastating, both to the affected child, and to the families involved, "unless we realize our obligation to screen and prevent these diseases in future generations, we won't act responsibly and invest adequate resources to increase the use of genetic screening," warned Schneider.
Since the number of diseases on the Jewish panel increased to 19 in 2011, "anyone screened before 2010 should have an update before each pregnancy. The new testing is 100 percent reliable."
The 19 diseases referred to above are: Bloom syndrome; Canavan disease; cystic fibrosis; Dihyrolipoamide Dehydrogenase Deficiency (DLD Deficiency); Familial dysautonomia; Familial hyperinsulinism; Fanconi Anemia Type C; Gaucher disease; Glycogen storage disease, type 1a; Joubert syndrome; maple syrup urine disease; Mucolipidosis IV (ML4); nemaline myopathy; Niemann-Pick Disease Type A; Spinal Muscular Atrophy; Tay-Sachs disease; Usher Syndrome Type 1F; Usher Syndrome Type III; and Walker-Warburg syndrome.