Jewish Thought and Law III Children

Tay-Sachs disease is a particularly tragic, inherited illness. A baby is born healthy, with no indications of an abnormality. Sadly, at approximately six months of age, the formerly cheerful baby gradually loses its previously gained milestones and undergoes physical and mental deterioration. The baby loses muscle tone and stops smiling, crawling, and turning over, losing its ability to grasp or reach out. Eventually, the child becomes blind, paralyzed, and unaware of the surrounding world. Death almost always occurs by age five.

The underlying defect in Tay-Sachs disease is a lack of an enzyme called hexosaminidase A, an enzyme that is necessary for breaking down specific fatty substances (ganglioside GM2) in brain and nerve cells. These fatty substances build up and gradually destroy brain and nerve cells, until the entire central nervous system stops working. While there are rare cases of later onset Tay-Sachs disease¹ (which may be less severe), the infantile type of Tay-Sachs is by far the most common.

Is there a Torah obligation to seek genetic screening for Tay-Sachs? If genetic screening is permitted or required, when should people be tested? To whom shall we reveal the results? Should we inform employers, insurers, and relatives? What are the ramifications of testing positive for an abnormal gene? Are there different ramifications of testing positive before versus after marriage?

In this article, we will use the gene for Tay-Sachs, found in high prevalence in the Ashkenazi Jewish population, as a representative example of the issues arising when testing for a recessively inherited disease.

A LESSON IN GENETICS

A gene vs. a disease
In order to understand the Jewish approach to genetic screening, background information is required. We must first make a clear distinction between a gene and a disease. One may carry a gene for a disease without manifesting any ill effects. One's genotype, or genetic makeup, is merely a description of a person's genes. If one expresses the trait coded for by the lethal gene, we say that his phenotype, or physical nature, is positive for the disease.

Modes of inheritance
Diseases may be inherited in several ways, the two simplest mechanisms being autosomal recessive and autosomal dominant. The cells of human beings carry two copies of the gene for each trait, however the copies may not be identical. One requires two genes for a recessive trait to be manifested, while one requires only one gene for a dominant trait to be manifested. For instance, one may carry a single gene for blue eyes and another for brown eyes, yet one's eye color will be brown, since brown eye color is a dominant trait. One would require two blue eye genes to actually have blue eyes.

Why do kids get Tay-Sachs and adults get breast cancer?

Offspring could develop the disease only if both parents are carriers and both passed it on to their child -- a one in four chance per pregnancy.

Recessively inherited diseases, such as Tay-Sachs, tend to affect children.² In such a recessively inherited disease, those with two defective genes would die as children, while people carrying one copy of the gene would be phenotypically normal, but risk passing the gene on to their offspring. Practically speaking, this means that for any lethal genetic disease that manifests exclusively before reproductive age, there must be many unaffected adults carrying the gene for the deadly disease in question. The only way (barring mutation) that the offspring of a carrier could develop the disease would be if their spouse also carried the defective gene and both passed it on to their child, a one in four chance per pregnancy.

This is both a blessing and a curse. Since carriers are healthy, there is no simple way to remove the gene from the gene pool. ³ We would have to bar all carriers from having children, a prospect which is both unethical and cruel. On the other hand, we could easily prevent the birth of babies with recessively inherited diseases (such as Tay-Sachs and cystic fibrosis) by preventing carriers from marrying.⁴

For any dominantly inherited trait or disease, only one copy of the gene for that trait is required, such as in the case of brown eyes mentioned above. Any child who inherits even one copy of the defective gene for a disease such as Huntington Disease (a lethal neurological disease) will almost certainly develop the disease, although the age of onset may be between two years and over 80 years. All lethal dominantly inherited diseases must have adult onsets or there would be no one to pass on the disease to the next generation. These diseases would also be virtually impossible to eradicate, since mutations are fairly common and we would have to forbid people who are currently healthy (but are likely to develop the disease) or already manifesting the disease, to marry. Some forms of breast and ovarian cancer demonstrate dominant inheritance.

Why screening for recessively inherited diseases is less traumatic
The Jewish community has had a lot of experience dealing with screening for recessively inherited diseases through Tay-Sachs testing programs for over 30 years. Because one is only testing for a gene, but not for a disease itself, there is a definite psychological benefit. There is no direct threat to the health of the person being tested. The carrier remains healthy following the discovery of the carrier state -- only potential offspring are affected. Additionally, knowledge of the carrier state empowers one to act to prevent the birth of children with a tragic disease. Therefore, the person being tested can retain their self-image of normal health.

The traditional Jewish community has been very receptive to Tay-Sachs testing. Jews have used the knowledge gained from testing to significantly decrease the incidence of Tay-Sachs births, with segments of the Orthodox community virtually eradicating Tay-Sachs births by an ingenious method of preventing carriers from marrying (which I will describe later in this article). Widespread testing has also been strongly encouraged by all segments of the Jewish community. Nevertheless, many issues arise even in testing for a recessively transmitted disease.

Is there a moral obligation to screen and if so, when?
While the Torah obligates us to guard our health,⁵ it does not necessarily follow that testing ourselves for recessive genetic traits (that do not directly affect our health) is included in the mitzvah. Nevertheless, Rabbi Moshe Feinstein favored Tay-Sachs testing and considered the possibility that testing might be a moral obligation.⁶ He states that while one may usually ignore a small risk that society finds acceptable (See: Taking a Risk),⁷ not being tested for Tay-Sachs is like closing one's eyes to an obvious danger. He also points out the severe emotional repercussions of not testing if a Tay-Sachs child is born.

Yet, Rabbi Feinstein feared that testing teenagers could hurt the self-image of those testing positive and lead to discrimination against them when seeking a spouse. He recognized that despite assurances from the medical community that carrying the Tay-Sachs trait presents no health issues for the individual or his offspring (so long as both spouses are not carriers), many people will shun marrying into a family with a genetic defect. Therefore, Rabbi Feinstein insisted on safeguards to protect confidentiality, advising testing of youngsters on an individual basis (and not mass screening), and only when he/she is prepared to start dating.

Dor Yeshorim
Rabbi Feinstein's approach is the approach of Dor Yeshorim, an organization that functions in the traditional Jewish community where formal introductions precede first dates. Dor Yeshorim carries the conclusions of Rabbi Feinstein to their logical conclusion. Being a carrier for Tay-Sachs does not impact on the health of the individual being tested and only affects potential offspring. Therefore, so long as marriage between carriers is prevented, there is no reason for anyone to be informed of the test results, including the prospective spouse and even the person himself!

Dor Yeshorim tests people for a variety of recessively inherited diseases,⁸ most notably Tay-Sachs, only informing matchmakers whether a prospective match presents a problem of genetic incompatibility.⁹Neither of the young people is told of their carrier status, but any potentially disastrous matches are averted. This anonymity is crucial in preventing Tay-Sachs status from causing emotional pain before marriage. It avoids initial emotional attachment between carriers by preventing their meeting, and prevents catastrophe after marriage (if two carriers marry). Dor Yeshorim has prevented many genetically incompatible matches before the couples ever met!¹⁰