January 25, 2001
A Decrease in Vigilance
Fewer couples are testing for Tay-Sachs and other Jewish genetic diseases.
A conference on genetic diseases held by the Cultural Foundation of Habib Levy in November led The Journal to examine the Jewish community's reduced state of awareness about genetic testing for prospective parents. During the past 30 years, large-scale genetic screening of Ashkenazi Jews in the U.S., Israel and other countries has reduced the number of babies born with Tay-Sachs, the most widely known Jewish genetic disease, by 90 percent. Yet today, younger Jews are less conscious of Tay-Sachs and even less aware of testing made available during the past five years for a newer array of genetic diseases. Geneticists and physicians confirmed that many people are not adequately informed about their genetic testing options. Regardless of their educational background, few individuals know if they fall into a high-risk category for genetically transmitted diseases. Experts interviewed maintain there has been a relaxation in vigilance about carrier screening and a consequential rise in danger signals for American Jews of Ashkenazi descent.
Dr. Dana Eisenman, a general internist with the Health Source Medical Group who spoke at the November conference, outlined some of the major genetic diseases that Jews need to be tested for: Tay-Sachs, Niemann-Pick, Gaucher, Canavan and cystic fibrosis. "Gaucher is the most common genetic disease in Jews," he said, "but it is less well-known than Tay-Sachs. Unlike Tay-Sachs, symptoms such as anemia, bone pain and fractures don't often show up until adulthood. For this disease there is replacement enzyme available that reverses many of these symptoms."
Cystic fibrosis causes mucus to build up in the bronchial tubes and the digestive system to fail to absorb nutrients. "In Ashkenazi Jews," Eiseman explained, "the carrier rate is one-in-40. As with the other genetic diseases, there is a 25 percent chance of a baby having the disease. Malnutrition and lung failure usually lead to death by the age of 30."
Tay-Sachs and Niemann-Pick, both caused by enzyme deficiencies, result in progressive brain damage and mental retardation from infancy, with death usually occurring in early childhood. Some variants of Niemann-Pick, which causes enlargement of the liver and spleen, turn up in older children, and one type does not affect the brain.
Unless there is a family history of one of these diseases, the issue of carrier genetic testing usually arises with a decision to have children. Until recently, the only commonly available tests were Tay-Sachs for Jews and sickle cell trait screening for African Americans. Eisenman stressed that today carrier genetic testing is available for all of these diseases.
"Each cell in our body has two sets of genes," he explained, "one set inherited from our mother, one set from our father. In most cases, only one normal gene of a pair is necessary for a cell to function normally. And so if a person has one defective Tay-Sachs gene from his mother but a normal gene from his father -- one bad gene, one good gene -- he will not have the disease. Now if the woman is also a carrier, each of the children of this couple has a one in four chance of having the disease.
"Through carrier genetic testing, the prospective parents can identify high risk pregnancies and then decide what to do," Eisenman said. "Any couple should avail themselves of all the tests for these rare diseases that could affect the fetus. Most insurance plans will cover these, if you're persistent about it."
Later, in a follow-up interview, Eisenman said that "it's really the diseases other than Tay-Sachs that are being ignored. I believe they should all be tested, even though the risk is maybe one in a thousand. If the mother is tested and she's negative, then it really doesn't matter what the father is.
"Probably the biggest threat to health resources is cystic fibrosis," he added. "One couple came from a family of doctors, but weren't aware of it and didn't test for it. One in every thirty white people carry the gene of cystic fibrosis. So that is probably the most important one to be tested."
"There's a decreased vigilance in the Jewish community even regarding Tay-Sachs," said Dr. Judith Tsipis, professor of biology and director of the genetic counseling program at Brandeis University. "I think that one in 25 Ashkenazi Jewish individuals are carriers of Tay-Sachs. In the late l960s, they developed a biochemical test to find out if someone was a carrier or not, and that enabled couples to make informed reproductive decisions. At that time a lot of people knew families who had children with the disease; it was very much on people's minds.
"What has happened is that the program has been spectacularly successful," Tsipis continued. "But the next generation no longer has that sensitivity to the issue, and they're still genetically at risk. College students, young couples getting married, rabbis counseling couples are not mentioning the possibility of carrier testing the way they used to. And that's a pretty disturbing trend. I certainly know of several couples who were not informed and who had children with Tay-Sachs recently."
Screening for Canavan disease -- also known as spongy degeneration of the brain -- is now urgently recommended, Tsipis stressed. "Whenever Tay-Sachs is discussed, Canavan should be discussed," she said. Canavan strikes one in 6,400 children, and there are only about 200 children in the U.S. with the disease. But once a child inherits two copies of the Canavan gene, the child's brain inexorably deteriorates, wiping out thinking, feeling, emotions, vision and muscle control. As the disease progresses, it causes seizures, severe feeding problems, retardation and blindness. Most children die between ages 10 and 15.
Tsipis -- whose son died of Canavan disease in 1998 -- explained the real story is the overall lowered awareness in the Jewish community: "You don't need to have a family history in order to be a carrier and at risk. People say, 'Gee, I don't need to be tested. I have no relatives with Tay-Sachs.' But that's not the way recessive inheritance works. It's two families coming together."
Dr. Ellen Knell, a geneticist at the conference who specializes in cancer risk assessment, underscored the concerns of Tsipis. "An awful lot of the young people who are of child-bearing age do not even know about Tay-Sachs," Knell told The Journal. "When the screening program was new, everybody got screened and everyone knew about it. But when have you last heard about it? "
Knell also pointed to the need to test for all of the five major diseases.
"The bottom line is that these diseases still happen," she said. "The carrier rate for Tay-Sachs is the same as it has always been, and there are about eight things one can do to not have a Tay-Sachs baby. The same applies to the other diseases as well. Depending on how religious you are, you can choose prenatal detection, with the option of aborting an affected child, because three-fourths will be normal. You can choose to have a donor sperm, artificial insemination from an unknown nonspouse. If you are very religious and are against these procedures, you can be anonymously tested and be introduced to someone who is not carrying the same mutations you might have. So there's a range of options. The important thing to me is that if you're unaware of all this and don't have any testing at all, you may have an unpleasant outcome that you were not aware could occur.
"Look," Dr. Knell said. "The only two ways that you find out if you're a carrier of an abnormal gene is one, to be tested or two, to have a child with that disease. Most people would choose not to bear and give birth to a baby that's going to die in three to five years. This is not past history. This is something that still needs to be dealt with. People are still getting these diseases."
For information about support groups related to genetic diseases:
National Tay-Sachs & Allied Diseases
National Society of Genetic
National Foundation for Jewish Genetic
National Niemann-Pick Disease