Work remains on Tay-Sachs and other Ashkenazi genetic disorders J. – The Jewish News of Northern California

In 1976, a letter to the editor thanked this publication for its coverage of the genetic disease Tay-Sachs, and for regularly promoting opportunities to get tested.

At the time, Tay-Sachs remained a scourge in the Jewish community. Since then, in a victory of community willpower over genetic destiny, a concerted push for early testing has virtually eradicated the disease reducing the number of Ashkenazi children born with Tay-Sachs from 60 per year, to 3 to 5 per year.

But while the incidence of Tay-Sachs among Ashkenazi Jews has fallen, a host of genetic disorders still threatens the community, necessitating genetic screening.

We need to plan and be proactive about it, said Estie Rose, a genetic counselor with JScreen, an Atlanta-based nonprofit that offers testing and education.

In 2008, the U.S. Senate named September Tay-Sachs Awareness Month, but Tay-Sachs is only one of the genetic diseases for which Ashkenazi Jews are more likely to carry a recessive gene. (A recessive gene, as opposed to a dominant one, is expressed only when inherited from both parents.)

According to Rose, about 75 percent of those with Ashkenazi Jewish heritage carry a recessive gene for at least one of a number of genetic conditions. Besides Tay-Sachs, the most common include Gaucher disease, cystic fibrosis, familial dysautonomia and Canavan disease. (According to the Jewish Genetic Disease Consortium, there are also various genetic diseases that are more prevalent among Sephardic Jews.) One in 30 Ashkenazi Jews carries the gene for Tay-Sachs, while among the general population, 1 in 300 is a carrier (the number is also high among those of Cajun descent).

While a recessive gene does no harm, a child with Tay-Sachs is more likely to be born to a couple who are both Ashkenazi Jews.

Its really only a problem if the person youre having a child with has the same gene, explained Mary Norton, an MD and professor of perinatal medicine and genetics at the University of California, San Francisco.

The reason Ashkenazi people are more likely to carry the Tay-Sachs gene is interwoven with the many calamities in the history of the Jewish people. Think the Crusades; think the Holocaust; think the Spanish Inquisition, Rose said. The size of the community shrunk, then it regrew.

For genetics, such circumstances exemplify a population bottleneck and the founder effect. In laypersons terms: Many Jews were killed at various times in history, leaving a smaller pool of genes to replenish the population. Also, Jews in Europe were endogamous, meaning they tended to marry other Jews.

The mutations become copy and pasted over and over and over again, Rose said.

Tay-Sachs was discovered toward the end of the 19th century, and even back then its prevalence among Ashkenazi Jews was noted.

The most common form becomes noticeable in infants around 6 months old. Symptoms include reduced vision and an exaggerated startle response, and then progress to slow growth, listlessness, neural degeneration and seizures by age 2, with death coming by age 5. The disease has no cure.

A carrier of a genetic disorder may have no family history of the disease or have the disease themselves. Pregnancy is often the first time many people get tested to see if they are carriers for a range of genetic disorders. Some dont get tested at all.

JScreens mission is to encourage people not to wait until pregnancy to get tested.

Thats what Rose did, and it changed her life. While in college, she and her partner got tested to see which genetic disorders they carried. It turned out they were both carriers for cystic fibrosis, a life-threatening disease. If shed had children with her then-partner, they could have faced some tough choices.

We decided to break up and avoid all of those things, she said.

Today, as a genetic counselor, Rose helps couples consider their options when faced with similar scenarios. She said JScreen tests for 225 diseases and works closely with the primary health care provider and genetic counselors.

I can serve my own community, which is really important to me, she said. The Jewish community unfortunately faces a lot of genetic health issues.

About 75 percent of those with Ashkenazi Jewish heritage carry a recessive gene for at least one of a number of genetic conditions.

Rose said if a pregnant couple finds they both carry the same disease gene, the next step is to test the fetus. If the fetus has the disorder, the couple has to choose whether or not to carry the baby to term. Even better is to do the testing before pregnancy, Rose said: In case there is a problem, they have more options.

The couple can explore IVF (in which each embryo can be tested before implantation) or egg donation, or they may decide not to have children or even go their separate ways, as Rose and her then-partner did.

Sophia Pesotchinsky is all in favor of testing before pregnancy. Her daughter Vera, 49, has Late Onset Tay-Sachs, a rare form of the disease.

The Pesotchinskys came to the Bay Area from Russia in 1976. Vera later developed motor function problems that turned out to be the first signs of LOTS. Sophia had never been tested to see if she was a carrier, neither in Russia nor here in the U.S. when she was considering having more children. Thats a huge oversight, she said.

If people have come from a different country, they have to be asked, Did you have that test? she said.

Thats particularly true for people who come from the former Soviet Union. Very often they didnt know they had Jewish roots, she pointed out.

Sophia said it took more than a decade to diagnose Vera (along the way, Sophia was told that her daughters problems, ranging from slurring to klutziness, came from having an overbearing immigrant mother). Vera, who earned an MBA from Santa Clara University and a BA from Wellesley College, is currently in a wheelchair and cannot live alone, but mother and daughter are active in patient advocacy through the National Tay-Sachs and Allied Diseases Association.

JScreen isnt the only Jewish organization trying to get people to screen early.

New York-based Dor Yeshorim screens potential couples in the Orthodox community by running tests for over 50 diseases. According to their most recent quarterly report, of more than 9,000 people who have used the service, 120 were found to be genetically incompatible.

Like JScreen, Dor Yeshorim advises people to get tested well before pregnancy. When a match is suggested its time for a compatibility check. Dor Yeshorim, rabbanim and experienced shadchanim urge everyone to check compatibility before a couple or the parents meet to avoid unnecessary heartache! the site says.

To that end, Dor Yeshorim often tests at Orthodox schools. JScreen works with Hillel and Birthright, Rose said.

Advances mean that genetic tests once reserved for Ashkenazi Jews can now be accessed by the population at large, further reducing the likelihood that children will be born with a disease like Tay-Sachs.

Tests used to cover only 25 or so gene disorders, but now hundreds can be identified.

Rose said its important to test no matter what ethnicity you are. While Ashkenazi Jews have their own set of risks, other ethnic groups have theirs. You never know what a test result will bring, Rose noted.

We all have things we dont know about our family history, she said.

Go here to see the original:
Work remains on Tay-Sachs and other Ashkenazi genetic disorders J. - The Jewish News of Northern California