September is Tay-Sachs Awareness Month, an opportunity to learn about this fatal genetic disease and the simple genetic screening test people can take before they start a family.

The statistics are sobering.

One in 30 Ashkenazi Jews, and one in 300 people in the general population, is a carrier of Tay-Sachs, a fatal chromosomal disorder that causes progressive neurological damage. Babies born with Tay-Sachs rarely live beyond the age of four.

However, thanks to more accurate and widespread screening in the Jewish community, the incidence of babies born with Tay-Sachs has dropped by more than 90 percent among Jews since the 1970s.

“The genetic screening offered today is fast, easy, and comprehensive,” Karen Grinzaid of JScreen said. JScreen is a nonprofit project that offers home kits requiring only a saliva sample to reveal if someone is a carrier of Tay-Sachs or about 200 other genetic diseases.

JScreen estimates that one in three Jews is a carrier for a genetic disease.

“When a couple is unaware of diseases they carry, the results can be devastating,” said Hillary Kener, who does national outreach for JScreen. “Any young adult planning to start a family or grow their family in the future should get screened. The history of Tay-Sachs in this country shows how genetic testing can positively influence people’s lives and the health of their children.”

Shari Ungerleider of Wayne needs no reminder.

As project coordinator at the Jewish Genetic Disease Consortium and a board member of the National Tay-Sachs and Allied Diseases Association, she is devoted to encouraging would-be parents to get tested in order to avoid the heartbreak of giving birth to a terminally ill child.

She and her husband, Jeff, endured this devastating scenario firsthand. Their firstborn, Evan, was diagnosed with Tay-Sachs at 13 months. He died in 1998 at the age of 4½.

“To honor Evan, I decided to turn our tragedy into something positive so that other families would be spared the suffering that we experienced,” Ms. Ungerleider said. “Having a child with a rare disease made me realize the importance of raising awareness about Tay-Sachs and the related genetic diseases.”

Evan Ungerleider died when he was 4 1/2; his mother’s Tay-Sachs test was misread.

Evan Ungerleider died when he was 4 1/2; his mother’s Tay-Sachs test was misread.

She was, in fact, tested for Tay-Sachs during her pregnancy with Evan and was told — erroneously, it turned out — that the results were negative. (If one parent tests negative, there is no need to test the other because a child can have Tay-Sachs only if both parents are carriers. Each child of two carrier parents has a 25 percent risk of having the conditions.)

Therefore, when the Ungerleiders took Evan for a pediatric checkup at 10 months and expressed concern that he wasn’t developing at the same pace as other babies his age, the doctor didn’t immediately suspect that he had Tay-Sachs.

All the specialists they consulted over the next three months asked if Ms. Ungerleider had been tested for Tay-Sachs. When she said she had, they saw no choice but to subject the baby to myriad diagnostic procedures to find some other explanation for his rapid developmental regression, which by now was causing feeding difficulties.

“Finally, at 13 months, a pediatric ophthalmologist discovered a cherry-red spot in Evan’s eye, which is indicative of Tay-Sachs,” Ms. Ungerleider said. “I called my OB/GYN to tell him they found this cherry-red spot. He called me back and said he had misread my Tay-Sachs test. I was a carrier. It was the missing piece to the puzzle, and the diagnosis was confirmed via blood work.”

The Ungerleiders channeled their grief into raising money for Tay-Sachs research and telling the story of their tragedy as a cautionary tale.

“In our work, we promote not just testing, but accurate testing,” Ms. Ungerleider said. “We also promote preconception carrier screening, because once you’re pregnant and find out the baby has a genetic disease, you have only two choices: to terminate or to have the child. Now there are so many options available to have healthy children if you find out you’re a carrier before conception.”

Among several options is preimplantation genetic diagnosis — PGD — to identify genetic defects in an embryo conceived through in-vitro fertilization. Another option is using donor sperm or eggs. Adoption, of course, is another alternative.

Ms. Ungerleider eventually gave birth to three healthy children, who are 14, 17, and 20 years old.

The Ungerleiders formed the Jewish Genetic Disease Consortium in 2005. Its goal is to educate physicians, rabbis, and the general community on the availability and importance of carrier screening. The group recommends that rabbis raise the issue during premarital counseling sessions.

“When JScreen started, we saw that they were offering a lot of the same educational programs and doing a good job of reaching people all over the country who might not have access to places to do screenings, so we began working together,” Ms. Ungerleider said.

“Carrier screening has changed so much over years, and JScreen makes it reasonable and offers counseling. Since not everybody really knows what their ethnic background is, it’s essential to have an expanded panel,” she added.

The JScreen “spit kit” can be ordered online at jscreen.org. The saliva sample is collected at home and mailed to the lab for DNA testing. The kit costs $149 with private insurance; people without private insurance may qualify for financial assistance.

If the test reveals an elevated risk for passing along any of more than 200 genetic disorders, certified genetic counselors associated with JScreen will contact the person to talk about results, options, and resources.

According to JScreen, a nonprofit public-health initiative based at Emory University School of Medicine in Atlanta, 80 percent of babies with genetic diseases are born to parents with no known family history of that disease.

JScreen reports that it detects nearly two times as many carriers of genetic diseases in people of Ashkenazi Jewish descent as in the general population. Like Ashkenazi Jews, French Canadians and Louisiana Cajuns are considered to be at high risk for carrying Tay-Sachs disease.