People of Ashkenazi Jewish descent have a higher risk of certain genetic diseases that range from mild to fatal. Parents-to-be may consider genetic testing because of the increased risk of potentially serious conditions.
Dr. Ellen Sidransky, Chief of the Medical Genetics Branch of the National Human Genome Research Institute of the National Institutes of Health, discusses prenatal genetic screening for Ashkenazi Jewish genetic diseases. She explains disease risk, what to expect with genetic testing, and how genetic counselors can help.
What Is Prenatal Genetic Screening?
“Prenatal genetic screening is a test done before a baby is conceived or born. It tests for variants in different genes that increase the likelihood of certain diseases,” says Dr. Sidransky.
People of Ashkenazi Jewish descent can do screenings before or during pregnancy to understand their odds of having a child with certain rare genetic diseases that are more frequently seen in the Ashkenazi Jewish population (Ashkenazi Jewish genetic diseases). It’s also possible to test a baby before birth (in utero) for most of these diseases.
According to Dr. Sidransky, one in three to one in four people of Ashkenazi Jewish descent are carriers of variants in one of the genes for diseases prevalent in the Ashkenazi Jewish population. Being a carrier means you have a variant (or mutation) in a gene for a disease, but you don’t have the disease. If you conceive a child with someone who also carries a disease- causing variant in that same gene, your child has a one in four chance of being born with the disease. Learn more about disease inheritance and genetics.
“If you find out you’re a carrier, then your partner can be screened. If your partner is also a carrier, you’ll know you’re at risk of having a child with one of these genetic diseases,” says Dr. Sidransky.
What Screening Is Available for Ashkenazi Jewish Diseases?
“Some screening panels may test for up to several hundred genetic diseases,” says Dr. Sidransky. “Other panels may check for 20 or so genetic disorders common in the Ashkenazi Jewish population. Gaucher disease is the most common of these and has a wide spectrum of severity.”
“Some of these diseases are lethal or can seriously impact someone’s life, but the severity depends on the disease,” says Dr. Sidransky. “Some diseases, like Gaucher disease type 1, are treatable.”
Examples of diseases included in Ashkenazi Jewish screening panels include:
- Canavan disease
- Cystic fibrosis
- Familial dysautonomia
- Gaucher disease type 1
- Mucolipidosis type 4
- Tay Sachs disease
Where Can You Get Screening for Ashkenazi Jewish Genetic Diseases?
“Different facilities do different panels, so first you must decide what type of panel you want,” says Dr. Sidransky. “Some of the facilities that offer genetic testing include universities, hospital systems, or independent screening businesses.”
The first step is typically to have your healthcare provider order the test. Your medical insurance may cover part of the cost of testing, which may be up to a few hundred dollars. Organizations like JScreen offer financial assistance for testing. Learn more about genetic screening resources.
How Does Screening Work?
Most current screenings look at DNA from a sample of:
- Amniotic fluid or placental tissue from a pregnant mother to test an unborn baby for the presence of genetic diseases
- Blood from one or both parents to test for carrier status
- Saliva from one or both parents to test for carrier status
Some saliva tests come as home kits that allow you to send samples through the mail for testing. The results of most screenings are available within days of the testing center taking or receiving your sample.
“Screening the parents tells you what genetic variants the parents are carrying, but not whether the baby will be affected,” emphasized Dr. Sidransky. “If both parents carry variants in the gene for the same disease, their baby will have a one in four chance of being born with the disease. But you still have to test the fetus or baby to know whether the disease is present.”
Prenatal Screening Is a Personal Decision
Not all couples want to know the disease risk for a child they conceive. “The information you get from screening can be either terrible or very reassuring, depending on the results,” says Dr. Sidransky.
The choice to screen can be impacted by what a couple would do with the information they receive from genetic testing. Some couples may choose to proceed with conceiving a child or completing a pregnancy regardless of test results, but others may make different choices.
Some couples may want to know their risk before conceiving a child. Others may want to do testing on a baby in utero so they can be prepared for their child’s medical needs if the screen comes back positive. If a fetus tests positive for a fatal disease, a couple may want to know early in the pregnancy. “This gives them the option of terminating the pregnancy if that’s their choice,” says Dr. Sidransky. “It’s a very personal decision.”
Genetic Counselors Can Help at Every Stage
Genetic counselors support you through the entire process. A genetic counselor can:
- Explain the science of genetic testing
- Walk you through the testing process and which disorders are being screened for
- Help you prepare for the possible results
- Support you through the emotions of testing and decision-making
- Explain the test results
- Give you guidance on what to do with the results and where to turn if you need further assistance
“Genetic counseling is really important, especially now with newer DNA screening techniques. People may do testing and end up with a lot of information that they don’t know what to do with,” says Dr. Sidransky. “A genetic counselor can help you understand what you’re getting into when you do genetic testing and help you at every stage.”
How the National Gaucher Foundation Can Help
If you or a loved one lives with Gaucher disease, the National Gaucher Foundation is here for your family. We offer resources to optimize your health with Gaucher disease and connect you with the support you need.
SOURCES
- NIH National Library of Medicine — Experience with Carrier Screening and Prenatal Diagnosis for Sixteen Ashkenazi Jewish Genetic Diseases https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2970726/
- NIH National Library of Medicine — Carrier screening in individuals of Ashkenazi Jewish descent https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3110977/
- National Gaucher Foundation — Genetic Disease Resources https://www.gaucherdisease.org/about-gaucher-disease/resources-genetic-diseases/
- National Gaucher Foundation — Gaucher Disease Inheritance and Genetics https://www.gaucherdisease.org/about-gaucher-disease/genetics/
