Tay-Sachs Disease

Topic Overview

What is Tay-Sachs disease?

Tay-Sachs is a rare disease that is passed down through some families. It harms the brain and nerve cells. There are two forms:

• The most common form develops soon after a baby is born. The child usually lives for 4 or 5 years.
• Late-onset Tay-Sachs can start between puberty and the mid-30s. How long a person lives depends on how severe the symptoms are. People may live as long as someone who does not have Tay-Sachs disease.

What causes Tay-Sachs disease?

Tay-Sachs can occur when parents pass on a changed (mutated) gene to their child.

• If a baby gets the gene from both parents, he or she will get the disease.
• If the baby gets the gene from only one parent, he or she will be a carrier. This means that the child will carry the changed gene but will not have the disease.

The changed gene keeps your body from making an enzyme called hexosaminidase A (hex A). Hex A breaks down normal fatty compounds (called gangliosides) in cells. When these fatty compounds are not broken down, they build up and damage brain and nerve cells, causing Tay-Sachs disease.

In late-onset Tay-Sachs (LOTS), the body makes a small amount of hex A. People with LOTS inherit the late-onset hex A gene from both parents or inherit one late-onset gene and one inactive gene.

The Tay-Sachs gene is most common in people of Ashkenazi Jewish descent. About 1 out of 30 people in this population is a carrier of the disease.^{1, 2} People of French-Canadian descent from the East Saint Lawrence River Valley of Quebec and people of Cajun descent in Louisiana are also more likely to carry the gene than others.

What are the symptoms?

A child with Tay-Sachs disease looks healthy at birth. But when your child is:

• 3 to 6 months of age, you may notice that your child makes less eye contact and has a hard time focusing his or her eyes on things. A doctor may see a red spot on your child's retina.
• 6 to 10 months of age, you may notice that your child is not as alert and playful as he or she had been. It might be hard for your child to sit up or roll over. You also may notice that your child does not see or hear well.
• 10 months and older, the disease gets worse quickly. Your child may have seizures, lose his or her vision, and not be able to move.

In late-onset Tay-Sachs (LOTS), early symptoms such as clumsiness or mood changes may be minor or seem “normal” and go unnoticed. Later symptoms may include muscle weakness and twitching, slurred speech, and trouble thinking and reasoning. The symptoms depend on how much hex A the body makes.

How is Tay-Sachs disease diagnosed?

If you or your doctor thinks your child has Tay-Sachs disease, your doctor will do a physical exam and a blood test to check the level of hex A. A genetic test may be needed to be sure the disease is Tay-Sachs.

How is it treated?

The focus of treatment for Tay-Sachs disease is to control symptoms and make your child as comfortable as possible. There is no cure. It may be helpful to seek counseling or find support from others who are going through the same thing you are.

If you develop late-onset Tay-Sachs disease (LOTS), treatment also focuses on controlling symptoms. The treatment you receive, such as medicine for depression, depends on the symptoms you have.

It may be overwhelming to learn that your child has Tay-Sachs. It’s important that you care for yourself as well as your child. Talk to your doctor about:

• Your concerns and the help you'll need for your child.
• A support group in your area.
• Family counseling to help each member cope with the disease.

As the disease gets worse, your child will need more care. Encourage your child to be as active as possible for as long as possible. Give your child your love and affection.

You may not be able to care for your child without help. Talk with your doctor about groups that can help you.

Should you get tested?

Carriers of the Tay-Sachs disease can pass the gene to their children even if the carriers don't have the disease. If both you and your partner are carriers, there is a 1-in-4 chance (25%) that any child you have will have Tay-Sachs disease.

If you are thinking about having a child, the American College of Obstetricians and Gynecologists (ACOG) recommends that:³

• Both of you be screened if you are both of Ashkenazi Jewish, French-Canadian, or Cajun descent or have a family history of the disease. If both of you test positive as carriers, genetic counseling may help you with making choices.
• You or your partner be screened if either of you is of Ashkenazi Jewish, French-Canadian, or Cajun descent or has a family history of the disease. If one of you tests positive for being a carrier, the other partner should be screened.

Frequently Asked Questions

Learning about Tay-Sachs disease:	What is Tay-Sachs disease? What causes it? What are the symptoms? What is late-onset Tay-Sachs disease?
Being diagnosed:	How is Tay-Sachs disease diagnosed?
Getting treatment:	How is Tay-Sachs disease treated?
Ongoing concerns:	What are the chances that my child will have Tay-Sachs disease?
Living with a child who has Tay-Sachs:	How do I care for my child?
End-of-life issues:	How do I cope with the death of my child?

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Author:	Debby Golonka, MPH	Last Updated: April 4, 2008
Medical Review:	Michael J. Sexton, MD - Pediatrics Siobhan M. Dolan, MD, MPH - Reproductive Genetics
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