Three decades after Jews began lining up for blood tests at synagogues, community centers and college campuses across the country, Tay-Sachs remains a dreaded disease.

But a truly rare one.

The incidence of Tay-Sachs among babies born to Jews in North America has dropped 95 percent since efforts began to combat the deadly disease that strikes Jews of Ashkenazi descent disproportionately.

In fact, most of the handful of babies born each year with Tay-Sachs are not Jewish, according to Dr. Michael Kaback, director of the California Tay-Sachs Disease Prevention Program in San Diego.

"There's been almost complete prevention in the Jewish population," said Kaback, whose state-funded center began a widespread screening and counseling program 30 years ago.

In 1970, there were about 100 newly diagnosed cases of Tay-Sachs annually in the United States and Canada, with 85 percent occurring in Jewish babies, according to Kaback. In 2000, there were about a dozen cases, two of which involved Jewish babies.

At UCSF Medical Center, "I think it was several years ago [when] we saw a patient with Tay-Sachs disease," said Dr. Seymour Packman, a professor of pediatrics. "I think that's to the credit of the screening program."

Tay-Sachs attacks seemingly normal babies at about 6 months of age with swift and devastating ferocity. Due to an accumulation of fatty substances in the brain, children lose their physical skills, become blind and mentally retarded and most die by the age of 5.

"There aren't words to describe it," said Dr. Susan Gross, director of reproductive genetics at Albert Einstein College of Medicine and Montefiore Medical Center in New York.

The carrier rate for the recessive Tay-Sachs gene is 1 in 27 among Ashkenazi Jews, compared with a 1 in 200 rate in the general population.

It takes two carriers to produce a Tay-Sachs child. Such a couple has a one in four risk that each pregnancy will produce a baby with the disease. Those couples often consider adoption, aborting fetuses shown by prenatal tests to be Tay-Sachs affected, artificial insemination or more rarely, a technique called pre-implantation genetic diagnosis.

The screening efforts are "truly one of the great success stories of public health," Gross said. "The families that might have been devastated once don't have to have that happen to their lives."

Gross is among a team of medical experts hoping to introduce a single screening test for some nine genetic diseases that are more common to Jews. She envisions a community-wide program modeled after the example set with Tay-Sachs.

"Genetics, instead of being frightening, can be empowering," Gross said.

The test being contemplated would screen for Canavan, Bloom syndrome, cystic fibrosis, Fanconi anemia, familial dysautonomia, Gaucher disease, mucolipidosis IV, Niemann-Pick disease and Tay-Sachs.

The cost for such a testing effort currently runs into "hundreds and hundreds of dollars" per patient and remains a "big stumbling block," Gross noted. Researchers hope to develop a less expensive and more accurate test.

Citing the collaboration between the Jewish and medical communities that resulted in widespread Tay-Sachs education and testing, Gross said, "The Jewish community has a tremendous amount to be proud of.

"We would like to duplicate it, just carry it forward into the next century."

The testing proposal isn't universally embraced, however.

"I have some reservations," said Kaback, noting that it's often a complicated process to inform patients about the implications involving a single genetic illness, let alone nine.

"We're talking about very complex and delicate issues," he said, noting that not all of the diseases have the disastrous consequences of Tay-Sachs. "I think we need to be careful."

Jayne C. Gershkowitz, executive director of the National Tay-Sachs and Allied Diseases Association, worries that a stigma may accompany testing for so many diseases.

"Many of these diseases, which occur disproportionately among people of Ashkenazi Jewish descent, also occur in the general public and other ethnic groups," she said.

She also questions how at-risk populations will be targeted and how carriers will be informed. "Say you're a carrier for two out of 10 [diseases]," she said. "How are they going to get the information?"

At Kaiser Permanente in Northern California, geneticists recently began discussing the possibility of adding screening for familial dysautonomia, a nervous system disorder, to an existing testing program for Tay-Sachs, Canavan and cystic fibrosis, according to Dr. Ronald Bachman, chief of genetics at Kaiser Permanente Hospital in Oakland.

He questions the notion of a whole panel of tests for other, less common or less severe illnesses, however.

Genetic testing goes far beyond a simple blood sample and involves careful education and counseling, Bachman and others said.

For many these days, the process starts in a doctor's office after a couple achieves a pregnancy. The preferred screening, however, takes place well before a patient even considers starting a family.

The state Tay-Sachs program continues its outreach on college campuses, conducting about a half-dozen yearly screenings at universities throughout Northern California alone. Overall, the effort tests 600 to 700 students annually.

This spring, a team traveled to Cabrillo College, a small community college in Aptos. The two-day effort screened 56 students, including 14 Jews and two from another at-risk group, French Canadians.

Students watched a video, filled out a form and got a blood test that will reveal whether they carry the Tay-Sachs gene. The idea is to identify carriers and provide them with information about the disease and its risks before they start planning a family.

"It's very scary," said 18-year-old student Rachel Sherer of Scotts Valley as she prepared to have her blood drawn. Sherer, who is Jewish, learned of the testing program in class. At home, "I really don't think we've ever talked about it," she said.

Michael Rancer of Piedmont wants to see a similar testing effort for familial dysautonomia or FD.

Two years ago, his 11-year-old son, David, died of FD, another fatal disorder that disproportionately strikes Ashkenazi Jews. Symptoms of the disease include an inability to digest food, aspiration pneumonia and uncontrollable body temperatures.

"It's a universally fatal disease," said Rancer. And while the carrier rate is similar to that of Tay-Sachs, "it's also a disease that's very hard to diagnose."

Following David's death, fellow congregants at Oakland's Temple Sinai raised money to mail packets of information about FD to 1,700 synagogues throughout the United States and Canada.

A screening test for FD was introduced two years ago and "we're trying very hard to get the testing out there with the same intensity you've seen with Tay-Sachs," Rancer said. As for treatment, researchers at New York's Fordham University recently reported that a variant of vitamin E had relieved symptoms in FD sufferers.

By offering screening and counseling programs to at-risk couples, medical specialists can "give people information so they can act accordingly," said UCSF's Packman.

While the diseases themselves may not be treatable, "what can be done is prevent the birth of a patient with an incurable disease."