Jewish Genetic Diseases
Getting Screened Before Pregnancy
There are many things to think about when deciding to have a baby. If you are Jewish, you should also be thinking about getting screened for Ashkenazi Jewish genetic diseases. Screening is simple and can provide you with valuable information to help with reproductive decision-making. The following information is meant to guide you through some of the commonly asked questions regarding Jewish genetic disease carrier screening.
What are Jewish genetic diseases?
Jewish genetic diseases refer to a group of diseases that occur with higher frequency in the Ashkenazi Jewish population. It is estimated that 1 in 5 Ashkenazi Jews is a carrier for one or more of these diseases. Ashkenazi Jews refer to those whose ancestors came from Central and Eastern Europe (i.e. Poland, Russia, Germany, Lithuania, etc.). The reason that Ashkenazi Jews are at higher risk than the general population is primarily due to the fact that the Jewish communities in Europe were small and isolated, and members tended to marry within those communities. Since it is estimated that all individuals carry a small number of gene changes (called mutations), the ones present in those small groups of European Jews became more prevalent in future generations.
What are the diseases?
There are currently 18 genetic diseases for which population screening is available for Ashkenazi Jews:
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Many of these diseases are life threatening and may be fatal in early childhood. Others cause life-long medical problems that greatly impact on the affected individual’s quality of life. While medical advances have led to improved management of some of these diseases, currently only Gaucher disease can be effectively treated with enzyme replacement therapy.
How are the Ashkenazi Jewish genetic diseases inherited?
The diseases mentioned here are inherited in an autosomal recessive manner. This means that, in order to have a baby with one of these diseases, both parents must be “carriers” for that disease and pass the gene on at the same time. Thus, the affected child inherits two copies of the gene change (mutation), and no copies of the normal working copy of the gene. Carriers have one copy of the gene mutation and one normal working copy of the gene. Carriers are healthy individuals with no signs of the disease, and they are not at risk to develop the disease. If both partners are carriers of a mutation in the same disease gene, there is a 25% chance of having an affected child, a 50% chance of having an unaffected child who is a carrier like themselves, and a 25% chance of the child being neither affected nor a carrier. In autosomal recessive inheritance, males and females are equally likely to be carriers and are equally likely to be affected (have a disease).
What is carrier screening?
Carrier screening is a simple blood test in which DNA is extracted from the sample of blood to look for the specific mutations commonly found in the genes for these particular diseases. Additionally, enzyme levels are measured from the same blood sample to screen for Tay-Sachs disease carrier status. Screening for many of the Ashkenazi Jewish genetic diseases is available through several different commercial labs, while screening for some of the diseases are only available on a more limited basis. Your doctor can help you arrange for screening, or he/she may refer you to a genetic counselor for more comprehensive screening.
What is the cost of carrier screening?
The cost of carrier screening can vary greatly from laboratory to laboratory. For many, health insurance covers the cost of carrier screening, so the cost to the individual is minimal.
What if I find out I’m a carrier?
Carriers are healthy individuals so it does not mean anything for your own health. Carriers can pass the gene mutation on to their children, so it is important that your partner be tested as well. It is only a concern if your partner carries a mutation in the same disease-causing gene. Genetic counselors can speak with you about these risks.
What if we are both carriers, can we still have healthy children together?
There are many reproductive options available to carrier couples, including prenatal diagnosis (chorionic villi sampling and amniocentesis), pre-implantation genetic diagnosis, gamete donation and adoption. Genetic counseling is recommended to learn more about all of your reproductive options. Additionally, your rabbi may be able to provide insight and help in making these decisions.
What if my partner is not Jewish? Do I still need to get screened?
We recommend testing if at least one partner in a couple is Jewish. This is because many of the diseases can occur in the non-Jewish population as well, although at much lower frequencies. In such a situation, it is best to test the person of Jewish background first, and then test the partner only if the first person is found to be a carrier.
What if I was screened several years ago? Do I need to repeat it?
You do not need to be screened again for any of the diseases you were previously screened for. However, the list of diseases for which screening is available may have increased, and will likely continue to change over time. Therefore, it is very important to check with us or your doctor before each pregnancy to update your genetic screening to include any new diseases that may have been added since your previous screening.