May 3, 2010 | 2:16 pm

Jews, Genes and the Talmud

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

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At the present time and for many millennia before, we physicians wait for people to get sick, and then we treat them with medication, surgery and other therapies.  But once we can construct a profile of every person’s genetic predisposition to disease, medicine will finally become predictive and preventive.  We are at the dawn of a new genetics—a paradigm shift from treatment to prevention, which is a result of the Human Genome Project (a 15-year, $3 billion quest), which maps every gene and discovers markers for hereditary disorders.  In the coming years, as medical researchers discover the molecular causes of various diseases, novel preventive strategies, new drugs, and eventually gene therapy will change the face of medicine. 

From the beginning of recorded history, humans have been intrigued by physical traits that run in families for generations – certain facial features, eye color, hair color, and various deformities.  Before the first scientific law of genetics was described by Gregor Mendel in 1865, ancient civilizations recognized the basic principles of heredity and used it in breeding animals and plants to improve their characteristics.

The Talmud (ancient Hebrew compendium of civil and criminal law) is generally not thought of as a medical textbook or a treatise on genetics, but this brilliant tome insightfully incorporated a provision that exempts a Jewish boy from circumcision if a maternal uncle (not a paternal one) is a hemophiliac (a person who bleeds excessively because of the absence of clotting factors).  This exception reveals a profound understanding by the sages of the Talmud on inheritance.

There are many types of hemophilia, with a higher number of the Type C (deficiency of factor XI) found in Ashkenazi Jews.  Clotting factor defects are genetic and genes determine everything physical about a person, including these factors.  A baby receives half of its genetic information from its mother (through the egg cell) and half from the father (through the sperm cell).  If the mother or father has the hemophilic gene, it may be passed to the baby through the egg or sperm.  Hemophilia C can affect both sexes and is autosomal in inheritance as the gene for factor XI is located on chromosome 4.  There are currently several treatments available to prevent bleeding in hemophiliacs, but gene therapy is on the horizon.  Basically, a healthy version of the defective blood factor gene is inserted into the hemophilic, which hopefully will change their genetic makeup, permitting them to produce normal amounts of clotting factors on their own.

In further articles, I will explore the answers to several questions:  “What is a gene?”, “What is a chromosome?”, What is inheritance?”, “If a genetic disorder runs in my family, what are the chances that my children will inherit the condition?”, “What is gene mutation?”, “What is gene therapy?”, “What is gene testing?”, “Will gene testing tell me if I am susceptible to a certain disorder?”, and “What are other genetic disorders that affect Jews?”

Finally, we are exploring the negative implication of gene defects on the Jewish people, but we should not forget the overwhelming positive aspects:  exemplary scientists, rabbis, writers, lawyers, doctors, nurses, businessmen, teachers, professors, and many, many Nobel Laureates.