I’m concerned that I may be a carrier for Tay-Sachs disease. What type of carrier screening will offer the most accurate results?
A combination of DNA and enzyme testing is strongly recommended for Tay-Sachs screening for the highest level of detection. Most labs only offer DNA testing for Tay-Sachs. Be sure to request a laboratory that performs both DNA and enzyme testing.
It is also important that your genetic screening is tailored to you and your family history. For example, individuals of Ashkenazi Jewish ancestry are known to have different mutations than individuals from the French Canadian population. It’s important to make sure that you do carrier screening specific to your ancestry.
Some labs offer expanded panels with many conditions aimed at couples with mixed or unknown ancestry. Discuss your interest in carrier screening with your genetics professional and determine which testing is best suited for you.
For more information, visit the Types of Screening page.
My enzyme carrier screening for Tay-Sachs disease came back as inconclusive. My provider wants me to have genetic testing for Tay-Sachs disease. Is it possible that I’m not a carrier?
Yes. Tay-Sachs disease enzyme analysis is very sensitive but can be affected by pregnancy status, medications, and transport temperature. DNA mutation analysis may help clarify whether an individual is truly a carrier for Tay-Sachs disease. Typically DNA and enzyme testing are performed at the same time to allow for optimal interpretation of results.
A genetics professional can help you to understand what this result means for you and your family. Visit Genetic Counseling to get in contact with a provider near you.
Genetic Testing Terminology
If you think of a gene as a page in a book, “gene sequencing” refers to reading across each letter of that page to see if there are any “spelling mistakes” in the genetic code. Gene sequencing would detect if “cat” in the book is misspelled as “ctt”. Some coding changes are normal and make us unique individuals. Other coding differences can result in disease.
A “variant of uncertain significance” or VUS is a coding change in your genes that has not been seen in enough people to thoroughly understand. We all have genetic variants that make us unique individuals. Some “variants” in your genes are normal and do not affect your health. It is also possible that a variant will eventually explain a disease in your family or increases your chance of having a child with a genetic disease.
Researchers are working to classify these variants and clarify what they mean for your family’s health. Most often a variant of uncertain significance is eventually determined to be “benign” or normal. It is a good idea to check-in with your genetics professional every few years to see if there are updates on your specific variant.
Known Carrier of Tay-Sachs Disease
If I am a carrier for Tay-Sachs disease or an allied disease, does that mean that I will get the disease?
No. Carriers do not express the symptoms of the disease. You need two mutated copies of a particular gene, one inherited from each parent, to develop an autosomal recessive disease.
For more information about autosomal recessive inheritance, visit the About Inheritance page.
My partner and I are both carriers for Tay-Sachs. We do not feel that we could handle the emotional burden of having a baby with Tay-Sachs disease. Is there anything we can do to ensure that we will have a healthy baby?
There are many reproductive options available to increase your chance of a having a healthy baby, specifically a baby that does not have Tay-Sachs disease. Some people choose adoption, others use sperm, egg, or embryo donation from non-carriers, some pursue a natural pregnancy with prenatal testing by amniocentesis or CVS, while others consider in vitro fertilization with pre-implantation genetic diagnosis (PGD).
For more information, visit the Family Planning page.
I am a carrier for Tay-Sachs disease and my husband is not. Is it possible for our children to be affected with Tay-Sachs disease?
Both parents need to be carriers for a child to be affected with an autosomal recessive disease like Tay-Sachs. However, there is a 50% chance with each pregnancy that your child will be a carrier (like you) and a 50% chance that your child will inherit two normal copies of the Tay-Sachs gene.
For a graphic explanation, please visit the About Inheritance page.
Finding out that you are a carrier while pregnant can be anxiety-provoking. Fortunately, you have several options that will help you better understand the risk to your baby.
The father of the pregnancy can pursue carrier screening to determine if he is also a carrier. If the father is not found to be a carrier, your baby is at very low risk for Tay-Sachs disease. If he is carrier, you can consider doing an amniocentesis or CVS. These are diagnostic tests that will be able to tell you if your current pregnancy is affected with Tay-Sachs disease or is unaffected.Speak with your obstetrician or genetics professional about this testing.
If your relative had a baby with Tay-Sachs disease, he or she is a carrier. If this is a blood relative, you may be at increased risk to be a carrier. It’s a good idea to discuss this family history information with your doctor or genetics professional. Remember, you are only at risk of having a child with Tay-Sachs disease if both you and your partner are carriers.
I’m French Canadian. My biochemical testing came back inconclusive and my sequencing came back normal. What should I do?
Carriers of French Canadian descent are more likely to have a mutation called a deletion; this means that a region of the HEXA gene is missing. If you think of the HEXA gene as a page in a book, screening by sequencing is only looking for single letter typos, but can fail to detect missing paragraphs. If you are French Canadian, ask your doctor or genetics professional to order genetic testing that will be able to find a large deletion, if present.
If I have late onset Tay-Sachs disease (LOTS), could I have a child with infantile or early onset Tay-Sachs disease?
All individuals with Tay-Sachs disease have a mutation in both copies of their HEXA genes. Some individuals with late onset Tay-Sachs disease have one late onset mutation and one infantile onset mutation. Others have two late onset mutations. If you have one infantile onset mutation and your partner does too, there is a 25% chance with each pregnancy that your child will have infantile or juvenile Tay-Sachs. If you have two late onset mutations and your partner is a carrier for late onset Tay-Sachs disease, your children are at risk for LOTS, but not early onset disease.
See the About Inheritance page for more information about autosomal recessive inheritance.