Tay-Sachs Disease

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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

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A baby with Tay-Sachs disease has no signs or symptoms of the disease at birth. Symptoms usually appear 3 to 6 months after birth. The symptoms are caused by damage to the brain and nerve cells from the buildup of fatty compounds. An early sign of the infantile form of Tay-Sachs is a red spot on the retina. See a picture of the retina.

Watch for the following symptoms if you suspect your baby may have Tay-Sachs disease.

At 3 to 6 months, you may notice:

• Decreased eye contact.
• Twitchy eyes (myoclonic jerks).
• Difficulty focusing on objects.
• Excessive startling by sharp but not necessarily loud noises.

At 6 to 10 months, you may notice:

• Limp and floppy muscles (hypotonia).
• Decreased alertness and playfulness.
• Difficulty sitting up or rolling over and a loss of motor skills.
• Decreased hearing and eventual deafness.
• Gradual loss of vision.
• An abnormal increase in head size (macrocephaly).

10 months and older

As a child with Tay-Sachs grows older, he or she may become blind, mentally retarded, paralyzed, and unresponsive to the environment. The child also may have seizures, difficulty swallowing, and difficulty breathing. Children with Tay-Sachs disease rarely live beyond 4 or 5 years of age.

Late-onset Tay-Sachs disease

Symptoms of late-onset Tay-Sachs disease (LOTS) usually develop between adolescence and the mid-30s. The symptoms vary among individuals, depending on the amount of hex A being produced by the body. At first, symptoms such as clumsiness or mood changes are subtle and may go unnoticed. Other symptoms that may develop include:

• Personality changes.
• Muscle weakness or twitching.
• Slurred speech.
• Impaired thinking and reasoning ability, such as memory problems, difficulty with comprehension, and short attention span.
• Inability to distinguish between what's real and unreal (psychotic episodes) or depression.

If your baby is suspected of having Tay-Sachs disease, a physical examination may reveal or confirm symptoms of the disease. A blood test (Tay-Sachs screen test) can determine whether your baby's body is producing the enzyme hexosaminidase A (hex A). The blood sample can be taken from a vein or from the umbilical cord immediately after birth.

If you are pregnant and are at risk for having a child with Tay-Sachs disease, the Tay-Sachs screen test can be done. A blood sample is collected from the placenta during chorionic villus sampling, or a sample of amniotic fluid is collected during amniocentesis. For more information, see the topics Amniocentesis and Chorionic Villus Sampling.

The Tay-Sachs screen test is also used to confirm late-onset Tay-Sachs disease in a teen or adult with symptoms of the disease.

A positive Tay-Sachs test may need to be confirmed with other genetic tests. For more information, see the medical test Genetic Test.

Screening for carriers

Knowing whether you are a carrier of Tay-Sachs disease is important because Tay-Sachs is an autosomal recessive disease. You have one gene that produces hex A and one that does not produce this enzyme. Your body probably makes about half of the normal level of hex A, which prevents you from getting the disease. But you can pass the gene on to your children. 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 considering having a child, the American College of Obstetricians and Gynecologists (ACOG) recommends that:³

• Both prospective parents be screened if both of you are Ashkenazi Jews or of French-Canadian or Cajun descent or have a family history of the disease. If both of you test positive as carriers, you should consider genetic counseling.
• You or your partner be screened if either of you is an Ashkenazi Jew or of 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.

Either hex A testing or DNA testing can be done.

In Ashkenazi Jews:³

• DNA testing detects 94 out 100 carriers.
• Hex A testing detects 98 out of 100 carriers.

Treatment is aimed at controlling symptoms. For example, your child may take medicine for seizures. There is no cure for Tay-Sachs disease.

Treatment for classical or infantile Tay-Sachs disease

If your baby has Tay-Sachs disease, other support measures may be needed as the disease progresses, such as:

• Family counseling to help family members cope with the disease and prepare for the loss of the child. For more information, see the topic Grief and Grieving.
• Help with the child's care (respite care or home health care) as the child's condition gets worse.
• A support group to share experiences with other families who are dealing with Tay-Sachs disease.

Treatment for late-onset Tay-Sachs disease

Treatment for late-onset Tay-Sachs disease (LOTS) also focuses on controlling symptoms. This form of the disease was recognized only recently, so not much is known about its course. But it is known that the nervous system effects get progressively worse over time. The treatment you receive, such as medicine for depression, depends on the symptoms you have.

You may need individual counseling to help control any behavioral or mental disorders that develop. Your family may need family counseling to cope with the disease and its effects. Although you may live as long as other people who do not have Tay-Sachs disease, you still need to have a living will and durable power of attorney. For more information, see the topic Care at the End of Life.

What To Think About

An animal study has used gene transfer to put hex A enzyme in the brain so it will move to the rest of the body where it is needed.⁴ Although preliminary, this study and other studies may offer future hope for Tay-Sachs disease treatment. Talk to your doctor for information about clinical trials and other research taking place.

Home treatment for Tay-Sachs disease consists of providing comfort and preparing for the course the disease will take.

If your child has Tay-Sachs disease, talk with your doctor about:

• Your concerns and the guidance you need to deal with your child.
• Whether there is a support group in your area. Talking with other families dealing with Tay-Sachs disease may be very helpful.
• The chances that a child you have in the future will have the disease. You and your spouse may need genetic counseling.
• Family counseling to help each member deal with the effects of the disease.

As your child with Tay-Sachs disease progressively gets worse, he or she will require increasing care. Encourage your child to be as active as possible for as long as possible. Give your child the love and affection you would give to any child. Your child will be as responsive and active as his or her mental and physical ability allows.

Some families find that they cannot care for their child at home without help. Talk with your doctor about options in your community, such as respite care and other home health services that help families care for their loved ones at home.

As the disease progresses, it is important that you allow yourself to grieve. For more information, see the topic Grief and Grieving.

Late-onset Tay-Sachs disease

If you have late-onset Tay-Sachs disease (LOTS), you may need individual counseling to control any behavioral or mental disorders that you develop. You and your family may need family counseling to deal with the effects of the disease. It probably will be hard to find a support group in your area, but talk with your doctor about organizations, local agencies, and Internet resources that may be helpful for you and your family.

Although you may live as long as other people who do not have Tay-Sachs disease, you still need to have a living will and durable power of attorney. For more information, see the topic Care at the End of Life.

Organizations

Related Information

• Ashkenazi Jewish Genetic Panel (AJGP)
• Genetics
• Grief and Grieving

Citations

1. Vallance H, Ford J (2003). Carrier testing for autosomal-recessive disorders. Clinical Laboratory Sciences, 40(4): 473–497.

2. Committee on Genetics, American College of Obstetricians and Gynecologists (2004). Prenatal and preconceptional carrier screening for genetic diseases in individuals of Eastern European Jewish descent. Obstetrics and Gynecology, 104(2): 425–428.

3. Committee on Genetics, American College of Obstetricians and Gynecologists (2005, reaffirmed 2007). Screening for Tay-Sachs disease. Obstetrics and Gynecology, 106(4): 893–894.

4. Martino S, et al. (2005). A direct gene transfer strategy via brain internal capsule reverses the biochemical defect in Tay-Sachs disease. Human Molecular Genetics, 14(15): 2113–2123.

Other Works Consulted

• Haslam RHA (2006). Degenerative diseases of the central nervous system. In FD Burg et al., eds., Current Pediatric Therapy, 18th ed., pp. 388–392. Philadelphia: Saunders Elsevier.

• Neudorfer O, Kolodny EH (2004). Late-onset Tay-Sachs disease. Israel Medical Association Journal, 6: 107–111.

• Ropper AH , Brown RH (2005). The inherited metabolic diseases of the nervous system. In Adams and Victor's Principles of Neurology, 8th ed., pp. 797–849. New York: McGraw-Hill.