• Program for Jewish Genetic Health

  • What are Jewish Genetic Diseases?

    Why Get Screened?

    How to Get Screened

    Where to Get Screened

    List of Diseases

    Options for Carrier Couples  

     

    Why Get Screened? 
    Be Prepared for Pregnancy 

    1 in 4 individuals who are of Ashkenazi Jewish ancestry is a carrier for at least one Jewish genetic disease. Carriers of these diseases exhibit no symptoms and usually do not have a family history of the disease. A carrier will only know of his or her status after a screening, or if he or she has a child who is affected with the disease.

    Screening is available for carriers of diseases that occur more frequently in the Ashkenazi Jewish population than in other ethnic groups. These types of diseases are caused by a mutation in the gene that has been inherited among many people of the population (“founder mutations”). A mutation means that the gene is altered and, as a result, does not work properly. When an individual has a mutation in either of his or her 2 inherited genes for a single disorder, that person is said to be a “carrier.” If both members of a couple are carriers of the same disease, there is a chance they both can pass down their mutations to their child—in that case, the child would be affected with the disease. This pattern of inheritance is called “autosomal recessive.”

     autosomnal recessive

    It’s not Just Tay-Sachs Anymore!

    Many of you may have heard of Tay-Sachs disease. With the introduction of community screening programs in the 1970s and private testing at physician’s offices, Tay-Sachs disease has been nearly eradicated in the Ashkenazi Jewish population. Today, more non-Jewish babies are born with this condition than are Jewish babies. Over the past several decades, other diseases have been identified, that, like Tay-Sachs, tend to be more common among this population and can be screened for carrier status. All of these conditions that can affect the offspring of carrier couples are serious diseases that can be fatal or have life-threatening symptoms. Each disease has a unique carrier frequency, effect on daily living, lifespan, and possible treatment (if any). A complete list and description of some of these conditions can be found here. With advances in gene discovery and technology, additional diseases that appear to be more common in the Ashkenazi Jewish population continue to be identified.

    Why us?

    The Jews of Eastern Europe (“Ashkenazi Jews”) have lived in small insular communities for hundreds of years. Mutations in genes were present in these communities, but were not common. The communities changed over time; there was migration outside, isolation, and a decrease in size. As a result, the mutations that had been rare earlier now became more prevalent, and a higher percentage of the population became carriers. This phenomenon is known as the “founder effect.”

    We are not the only population to have high carrier frequencies for this reason. For example, sickle cell disease tends to affect African-Americans, beta thalassemia affects Mediterranean populations, and Tay-Sachs disease is also common among the French Canadian, Irish, and Louisiana Cajun populations.

    How one identifies with their religion does not define their ancestry. An individual does not need to practice Judaism to be considered Jewish. If an individual has at least one grandparent who descended from an Ashkenazi Jew, that person is at risk of being a carrier for a Jewish genetic disease. Therefore, these individuals should be screened.

    What else needs to be addressed?

    At this time, testing performed at settings like community screens is done for autosomal recessive diseases common in the Ashkenazi Jewish population only. A referral to a geneticist or genetic counselor can be made for testing for other common conditions such as hereditary breast and ovarian cancer, spinal muscular atrophy, fragile X syndrome, and recessive diseases that are common in the Sephardic Jewish population.  

    Learn more by viewing our MyJewishGeneticHealth.com Public Service Announcement on Pre-Conception Carrier Screening and register at MyJewishGeneticHealth.com for access to the full related lesson.

    Click to read a statement of endorsement for pre-conception genetic carrier screening, signed by Roshei Yeshiva.

     

    How to Get Screened

    Screening for carrier status for a panel of genetic diseases more commonly found in the Jewish population is done with a simple blood draw. The blood is sent to an accredited laboratory and DNA is extracted. Specialized genetic tests are performed to look for the presence of mutations (changes) that are commonly found in Ashkenazi Jewish carriers in each of the genes. For Tay-Sachs carrier screening, an additional test is done that is called the HexA enzyme assay. This test looks at levels of the specific enzyme that is reduced in Tay-Sachs carriers and deficient in babies with Tay-Sachs.

    A report with the results is written, and indicates whether or not the individual is a carrier for any of the diseases. As with any genetic test, the results that are reported are the most accurate for the time they are given. There is a slight possibility that there are disease-causing mutations in other regions of the genes analyzed or in other genes. This “residual risk” will be written on the report.

    It is very important that a genetics professional or trained physician reads the results carefully and gives a copy of the report to the patient only. It is up to the individual to decide whether or not to share this information should be shared with family members. Of course, we encourage those with positive results to share because direct relatives of an individual with a mutation have a higher chance of being a carrier than those in the general population. As the testing panel may expand in the future, it is important for the individual to keep his or her report for updating.

    Where to Get Screened 

    There are various options available for people who wish to be screened:

    Genetics Office

    If one chooses to go to a genetics office, he or she will meet with a genetic counselor and/or medical geneticist. The counselor will take a complete family history and will assess the individual’s needs for genetic testing. The counselor will recommend certain tests and will discuss options for the future. Genetic counselors have up-to-date knowledge of testing recommendations.

    The results will be ready about 2 weeks later, and the counselor will review them with the patient. If the patient is found to be a carrier, the counselor will encourage his or her partner to get tested for the same disease. If both members of the couple are carriers, the genetic counselor will help facilitate discussions about family planning. Couples who are carriers are offered many reproductive options to avoid having an affected child. A discussion of these options can be seen here.

    Genetics offices are often located at academic medical centers. Most genetic counselors are allotted enough time to have detailed discussions about their patients’ family and medical histories and to describe the screening process. If a medical concern in the family history that does not pertain to the Jewish diseases is revealed, the genetic counselor will address that as well. Genetic counselors are trained to attend to the genetic and psychosocial needs of the patient.

    The cost of getting screened at a genetics center depends on one’s health insurance. Some insurance companies will cover the cost of the screening and genetic counseling in full, while others might partially cover it or not cover it at all. This will be discussed at the time your appointment is made.

    To make an appointment for your genetic screening with us at the Division of Reproductive Genetics at Montefiore Medical Center, register at www.PJGHtesting.com.

    Physician’s Office

    Often a woman who goes to her OB/GYN for a preconception or prenatal visit will be asked of her ancestry. If she is Jewish, the physician will either send the patient’s blood sample to a lab or will refer the woman to a genetics office.

    Many women may feel more comfortable with their regular OB/GYN and are encouraged to continue with them if they desire. If a woman decides to go this route, she must make sure to keep track of the tests that are being performed by her physician, as more tests may be available in the future.

    Community Screening Events

    Genetics centers may “take their show on the road” and plan a screening of many individuals at once. This route is often convenient for the patients, because these events usually take place on college campuses, synagogues, and Jewish community centers. The cost of getting screened at a community screening event varies. The details about cost will be specified for each event. Advertising for these events may begin months before the actual screening.

    At the screening event, individuals may meet one-on-one with a genetic counselor or may have a group session outlining the process. Results from these large community screens may take up to 8 weeks to get to the individuals screened. If an individual is found to be a carrier, he or she will be contacted by a genetic counselor.

    For a list of our upcoming Program for Jewish Genetic Health screening events, click here.

    Dor Yeshorim (“Closed testing”)

    Dor Yeshorim is a genetic screening organization that was designed to cater to certain Orthodox communities who wish to protect themselves from possible stigmatization as a result of being a carrier. The process is quite unique in that the tested individuals do not receive a copy of their results, and never know their precise carrier status. Instead, they are given an identification number and are instructed to call the organization using their number when they are considering a relationship. Both members of a couple, therefore, must do their screening through Dor Yeshorim if they wish to have this type of “closed testing.” If a couple’s “numbers” are not compatible based on carrier status, they may decide not to continue to relationship.

    What is most important is not how one chooses to get tested, but that they take the initiative to do it. Don’t wait until it’s too late.

    List of Ashkenazi Jewish Genetic Diseases (Click here for a printable copy)

    2013 Disease table page 1

     2013 Disease table page 2

     

    Please call us at (718) 430-4156 with any questions.

    Options for Carrier Couples

    If both members of a couple are found to be carriers for the same disease, there are several options for family planning. Some couples may choose to get pregnant and then find out if the fetus is affected (with the option of terminating the pregnancy). Others would rather avoid getting pregnant with an affected fetus from the very beginning. Consultation with a rabbi, spiritual leader or mental health professional may be appropriate for those who need help deciding which option is best for them.

    Before a Pregnancy: Not leaving things up to chance

    1) Preimplantation Genetic Diagnosis (PGD)
    PGD is performed as a part of an In Vitro Fertilization (IVF) cycle. Multiple eggs are produced by the woman through rigorous hormone stimulation. They are then retrieved from her ovaries and fertilized with her partner’s sperm in a laboratory setting. Once the embryos that are produced from this union reach the eight-cell stage, one of those cells is extracted from each embryo. That one cell is tested for the disease in question. If the cell shows to have 2 mutations (affected with the disease), the embryo from which it came will not be implanted in the woman. Only embryos that are not affected will be implanted.

    PGD is an excellent option for carrier couples because it is a means to circumvent the potential issues that may arise once a carrier couple is already pregnant. However, diagnosis by PGD is not perfect. Fetal testing via CVS or amniocentesis (see below) is recommended in conjunction with PGD. The cost of IVF with PGD is high, varies from center to center, and not all health insurance plans will cover the costs. A genetic counselor or OB/GYN can make referrals to specialists in assisted reproductive technology, such as PGD.  Click to watch a short video on pre-implantation genetic diagnosis at our MyJewishGeneticHealth.com online education series and then register at the site to access the full PGD lesson, including a webinar from Dr. Harry Lieman, PJGH Liaison for Fertility and Reproductive Technologies.

    2) Egg or Sperm Donation
    If both members of a couple are carriers, another option is to use the gametes (i.e., egg or sperm) of only one of the two. Individuals who choose this option use egg or sperm donors that have been screened for the disease in question and are found not to be carriers.

    3) Adoption
    Couples who wish to have a child, but are both carriers for a fatal disease, may decide to adopt.

    During a Pregnancy: Ways to test the fetus to see if it is affected (prenatal diagnosis)

    1) Chorionic Villus Sampling (CVS)
    In this medical procedure, a small sample of the placenta is extracted through the woman’s abdomen or cervix with a thin needle, under ultrasound guidance. This sample is sent to a lab, where fetal testing is performed. The results of this test will tell the couple if the fetus is affected. CVS is performed between 10-13 weeks of pregnancy.

    2) Amniocentesis
    In this medical procedure, a small sample of amniotic fluid is extracted through the woman’s abdomen with a thin needle, under ultrasound guidance. Like a CVS, this sample is sent to a lab, where fetal testing is performed. The results of this test will tell the couple if the fetus is affected. This procedure is performed between 16-22 weeks of pregnancy.

    Both CVS and amniocentesis have a slight risk of miscarriage (about 1 in 500). It is recommended that couples who choose to have either one of these procedures have it done in conjunction with genetic counseling in an experienced center.

    To make an appointment with us at the Division of Reproductive Genetics at Montefiore Medical Center, register at www.PJGHtesting.com.

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