Jewish Journal

An introduction to Jewish genetic diseases: Part I

by Norman Lavin, M.D, PhD., UCLA Medical School

January 24, 2011 | 10:15 am

The following is an introduction to Jewish genetic diseases, which I will explore in greater detail with you – the reader – over the next two years.  I will attempt to provide answers to some of the many questions asked by potential parents and others in the Jewish community on genetic testing, screening, diagnosis, and treatment. At the end, I will provide resources to seek additional genetic information and counseling.

The first step towards unraveling the mysteries behind genetic disorders is to find the defective gene.  Over 4000 genetic diseases are known and many of these cluster among members of specific ethnic groups such as the Jewish people. Unfortunately, many of these diseases are debilitating and may result in early death.

Why Perform Genetic Testing?

Genetic testing is a procedure that analyzes genes which can provide information about the health of an individual or the potential health of a newborn baby.  The Human Genome Project,  (launched in 1988), was an attempt to characterize specific genes allowing detection of specific diseases, as well as diagnosis, screening, counseling, prevention, treatment, and theoretically cure by gene replacement or other correction procedures. Geneticists seek to understand the inherited basis of human diseases enabling improved diagnostic tests and ultimately the cure for these horrific disorders.  This genetic project invites ethical, legal, and social questions with literally tens of thousands of responses by ethicists, philosophers, professors, and clergy.  After many years in which the study of complex human traits was mired in false claims and inconsistencies in methodology, this genomic program has brought not only better understanding of human variation, but also welcome rigor in the interpretation of statistical evidence.

Why would an individual want Genetic Testing?

If a genetic disease exists in a particular family, a family member might want to know if he or she might get the disease or they may want to know what the possibility is of getting the disorder because of their affiliation with a particular ethnic group such as Judaism. On the other hand, an individual might be experiencing signs or symptoms reflecting an underlying genetic disease.

The Genome Project and Judaism

Does genetic engineering change the Divine arrangement of Creation?  Some rabbis say yes, but most consider the acquisition of knowledge for the sake of providing cures for human illnesses to be divinely sanctioned, if not, in fact, mandated.  The pursuit of scientific knowledge is not considered to constitute prohibited eating from the Tree of Knowledge (Genesis 2:17).   

Ancient Jewish Writings

The subject of genetics is sprinkled throughout the Bible and Talmud.  One writer describes how the laws of Mendelian genetics were applied by Jacob in the biblical narrative (Genesis 30:32) of the speckled and spotted sheep.  Hemophilia (described in one of my previous articles on the Blog)) and its precise genetic transmission is described in the Talmud (Yevamot 64b).  The sages had a surprisingly remarkable knowledge of the genetics of this sex-linked disorder and the rabbis at the time recognized that females transmit the disease, but do not suffer from it, although a few rabbis also considered the possibility of its transmission through males.  Genetic disease was also recognized by Maimonides.

Premarital Screening/Amniocentesis

Debate continues about the screening of large populations of Jewish people for the carrier state of Tay-Sachs disease, as well as other genetic disorders, to prevent inappropriate “marriage to carriers.”  Another controversy is the performance of amniocentesis for the prenatal detection of this fetal disease with possible abortion of an affected fetus.  Termination of these fetal diseases by abortion may not be acceptable in Judaism, although some rabbis might sanction such a procedure. Rabbi Eliezer Yehuda Waldenberg allows abortion following amniocentesis during the first trimester if Tay-Sachs disease is diagnosed.  Conversely, Rabbi Jay David Bleich states that abortion may not be sanctioned.

Should a carrier of the Tay-Sachs gene, for example, refuse to marry a mate who has not been tested?  Should two carriers break up an engagement if they learn that both are carriers as a result of a screening program?  Should a young person inquire about the Tay-Sachs status of a member of the opposite sex prior to meeting that individual on a social level?  Must a person who knows that he or she is a carrier divulge this fact to an intended spouse?

Newborn Screen

Newborn screening shortly after birth can detect certain genetic diseases, such as phenylketonuria or hypothyroidism, and can be treated immediately with the infant growing up physically normal. 

Preimplantation Diagnosis  

Genetic testing can also be performed at different stages of human development and life.  One example is pre-implantation diagnosis of several genetic disorders whereby individual cells of a fertilized egg are tested for a mutant gene or a gene product.  For example, two married carriers of the Tay-Sachs gene can choose to discard an affected zygote, (an early embryonic structure), and then only implant an embryo free of the genetic disease into the mother’s womb to prevent the birth of an affected baby.. 

There are many pitfalls, including inconclusive linkage studies, insensitivity of the specific test, variable expressivity of the gene, laboratory quality control, and misinterpretation of test results.  There are also concerns about genetic discrimination and confidentiality of test results.

There are many more questions, such as who owns genetic information, how should genetic information be used, and who decides who should be screened?  Should there be limits to pre-implantation, prenatal and neonatal screening?  And how should employers and insurers utilize genetic information?

Commentary on Genetic Screening

There are two methods to eliminate the need for prenatal screening for Tay-Sachs disease and the Halachic objections to abortion if the fetus is found to be affected.  The first is to perform confidential premarital screening and to strongly discourage the marriage of the two carriers.  This approach has been used in Israel since 1986 and has resulted in no Tay-Sachs children being born to newlywed couples in the ultra-Orthodox Ashkenazi Jewish community.  The second method, which we will discuss in greater detail, is to prevent the birth of a Tay-Sachs baby by pre-implantation screening of the in vitro fertilized zygote.  This procedure is performed if both the husband and wife are known carriers and then use only the healthy zygote for implantation.  The discarding of the affected zygote is not considered as abortion since the status of a fetus or a potential life in Judaism applies only to a fetus implanted and growing in the mother’s womb.

Gene Therapy/Genetic Engineering

Gene therapy, such as the replacement of the missing enzyme in Tay-Sachs disease or the missing hormone in diabetes or the repair of the defective gene in hemophilia or Huntington’s disease is probably sanctioned in Jewish law because it is meant to restore health and preserve and prolong life. 

Another argument supporting genetic manipulation is the fact that the sperm or ovum or even the fertilized zygote is not a person.  The potential human being status in Jewish law is only bestowed upon a fetus implanted in the mother’s womb.  Rabbi Moshe Hershler supports genetic engineering and gene therapy, but still asks the question whether these procedures may be prohibited because he who changes the Divine arrangement of Creation is lacking faith in the Creator.  Rabbi Shlomo Zalman Auerbach and Yeshua Jaynuerth support these procedures – they believe that the main purpose of gene therapy is to cure disease, restore health, and prolong life -  all goals within the physician’s divine license to heal. 

I believe that genetic engineering and gene therapy can and should be used to treat, cure, and prevent disease, but the question arises whether these techniques should be allowed to alter human traits, such as eye color, height, personality, intelligence, or facial features


The scientific community is moving forward in the quest of curing Jewish genetic diseases, but current rabbis should examine these issues from the Jewish viewpoint and offer Halachic guidance to the medical and lay communities.

Judaism supports premarital screening for the purpose of discouraging at-risk marriages for a fatal illness such as Tay-Sachs disease.  Neonatal screening is encouraged as it can provide avenues of treatment for disorders such as Phenylketonuria.  Pre-implantation screening, using only healthy zygotes for implantation into the mother’s womb, is also probably sanctioned in Jewish law, but further discussion is ongoing.  Prenatal screening with a specific intent of aborting an affected fetus is not allowed according to most rabbinic authorities.  Not to have   children if both parents are carriers of genetic diseases, such as Tay-Sachs, is not a Jewish option.  Pre-implantation screening is preferable.  To improve physical traits, such as height, eye and hair color is frowned upon in Judaism if it serves no useful medical or psychological purpose.  Finally, the cloning of man is prohibited as a violation of the Divine arrangement of the world and the creation of man in the image of God.

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Norman Lavin, M.D.,PhD.
Clinical Professor of Endocrinology
Director of Endocrinology Education
UCLA Medical School

Director of the Metabolic, Diabetes, and Weight Control...

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