CHICAGO — There's a catch-22 in the medical community regarding screening for Jewish genetic disorders.

Three decades ago, many people in the Jewish community knew someone with a baby who suffered from Tay-Sachs disease, according to Dr. Joel Charrow, head of clinical genetics at Children's Memorial Hospital in Chicago and an executive committee member of the Chicago Center for Jewish Genetic Disorders.

Since then, cases of babies born with these debilitating diseases have plummeted due to screening programs that detect the carrier status of parents.

As the disorders disappear from the Jewish radar, though, the illnesses are less discussed in the Jewish community. Increasingly, young Jewish newlyweds are in the dark about genetic disorders and don't have the tools to prevent the diseases from striking their own blooming families.

At the Chicago Center for Jewish Genetic Disorders, Karen Litwack, the director, says knowledge is the key to prevention. The center, created in 1999 and the only one like it in the country, acts as a voice in the Jewish community, translating medical research into accessible information for individuals and families through public education and awareness, professional education, screening and prevention programs, and advocacy.

Most physicians advocate screening, particularly among Ashkenazi Jews, who are most susceptible to the most common Jewish genetic disorders. The diseases may affect Sephardi Jews and non-Jews, but they afflict Ashkenazi Jews as much as 20 to 100 times more often, according to the center.

"My personal recommendation is that every Jew of reproductive age should be screened, ideally prior to first pregnancy," Charrow said, "and I recommend that both members of a couple be screened if one or both of them are Jewish."

Genetic screening consists of a simple blood test given to identify defective genes capable of causing hereditary conditions.

Abnormal genes for certain Jewish genetic disorders — the most common are Tay-Sachs disease, Canavan disease, Gaucher disease and Bloom syndrome — are silently passed down through the generations in an inheritance pattern called autosomal recessive, according to the National Foundation for Jewish Genetic Disorders.

In autosomal recessive inheritance, two copies of the same gene are needed to have an affected child. If both parents carry a particular gene, there is a 25 percent likelihood in each pregnancy of having a child with the disease. If a couple discovers that each partner carries the genetic defects, after the woman becomes pregnant they can determine, through prenatal diagnosis, whether the embryo or fetus has inherited the abnormal gene.

Rabbinical and medical communities — for the most part — agree that screening is key to maintaining a healthy Jewish population.

"Judaism has always embraced medical knowledge [and strives] to use it in a positive way," said Rabbi Debra Newman Kamin of Am Yisrael Conservative Congregation. "So if something can be done to prevent children born with Jewish genetic diseases, we do not shy away from doing it."

Orthodox rabbis encourage screening as well. "Finding out potential genetic problems is certainly something that the Jewish tradition and all of its expression wants to have happened," said Orthodox Rabbi Yehiel Poupko, Judaic resources consultant for the Chicago-area Jewish federation. "It's the way we protect life. It's the way we improve the quality of life."

The debate in the Jewish movements lies in what to do with the information once a screening has taken place. Dor Yeshorim, a New York-based, active screening program in the Orthodox community, provides medical information for couples to help them make informed decisions on marriage.

If couples educate and screen themselves, Charrow says, hope abounds. If both members of a couple are carriers, they have several options besides risking the chance of conceiving an affected child. They can use artificial insemination or egg donation.

Pre-implantation diagnosis, still in the experimental stages, is another alternative: A diagnosis takes place in the early embryonic stage, using in vitro fertilization. If the embryo does not have a genetic defect, it can then be implanted into the uterus.

"The availability of screening and prenatal diagnosis," Charrow said, "has enabled families to grow and couples to have more children with the security that their children will not have one of these diseases."