Jewish Genetic Disorders
We all carry changes in our genes that can lead to disease. Many ethnic groups have “their own” genetic disorders — disorders that are not unique to the group, but are found to be more common in individuals from that particular ethnic background. In the Ashkenazi Jewish community (Jews of eastern European descent) there are a number of conditions that are seen more frequently than they are in the rest of the population. Certain disorders tend to be more common among Ashkenazi Jews due to the “founder effect.” For centuries, for political and religious reasons, Ashkenazi Jews were genetically isolated from the population at large. The founder effect occurs when populations are started from a small number of individuals of an original population. Geneticists refer to this relatively small group of ancestors as “founders.” It is believed that most of today’s Ashkenazi Jews descended from a group of perhaps only a few thousand Ashkenazi Jews that lived 500 years ago in Eastern Europe. Today millions of people may be able to trace their ancestry directly to these founders. Thus, even if just a few founders had a genetic mutation, the gene defect would become amplified over time.
Some of these genetic alterations can cause severe and even fatal diseases. This occurs only when a child inherits a copy of the altered gene from both parents, and therefore has two altered copies and no normal copy. Individuals who have one normal copy of the gene and one altered copy of the gene are called “carriers,” because they “carry” the altered gene, but do not have the disease - the normal copy “protects” them. When both partners in a couple are carriers of the same genetic alteration, there is a 1 in 4 chance that any child of theirs will get the altered copy from both parents and therefore have the disease.
Genetic carrier screening identifies individuals who have a single copy of a gene which is associated with a severe disease. It is recommended for all individuals of reproductive age who have Ashkenazi Jewish ancestry as a part of family planning, prior to conceiving a pregnancy. If both partners in a couple are found to be carriers for the same disorder, there are a variety of reproductive options for reducing the chance of having a child with that disorder, from 1 in 4 to a negligible risk. Screening involves a collecting a blood or saliva sample. There are at least 19 genetic conditions currently considered to be more common in individuals of Ashkenazi Jewish ancestry included in most screening panels. The recommendations continue to change with new discoveries, so it is important to check in with the Center for Jewish Genetics for any updates that may be suggested.
There are also some conditions found frequently in individuals of Sephardic background. The genetic disorders that are common among Sephardic Jews vary based on country of origin. The Center also offers a comprehensive panel which includes conditions seen in the Sephardic population, the 19 in the Ashkenazi population, plus more than 60 other conditions that are inherited in the recessive fashion.
Genetic testing may not be appropriate for everyone, but it can be helpful for you and your doctor to know about the increased health risks so that together you can plan for a healthy future. For more information about Jewish Genetic Disorders and carrier screening programs in your area, please visit the Center for Jewish Genetics at www.jewishgenetics.org.