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Tay-Sachs Disease
Topic OverviewWhat is Tay-Sachs disease?Tay-Sachs disease is a rare genetic disorder in which little or no hexosaminidase A (hex A) enzyme is produced by the body. Hex A is necessary to break down normal fatty compounds (called gangliosides) in the body cells. When these fatty compounds are not broken down, they gradually accumulate and damage brain and nerve cells, making the cells unable to function properly. There are two forms of Tay-Sachs disease:
What causes Tay-Sachs disease?Tay-Sachs disease is an autosomal recessive disease. This means that to have the disease, you must inherit a gene for the disease from both parents. If you inherit the gene from only one parent, you are a carrier, meaning that you carry the gene for Tay-Sachs but do not get the disease.
What are the symptoms?A baby with Tay-Sachs disease appears healthy at birth. Symptoms usually first appear 3 to 6 months after birth, beginning with mild motor weakness and occasional twitches of the eye (myoclonic jerks). By 6 to 10 months of age, the baby's motor skills may be lost. After this, the disease progresses rapidly to seizures, blindness, paralysis, and death at age 4 to 5. In late-onset Tay-Sachs (LOTS), the symptoms may be subtle (such as clumsiness or mood changes) and go unnoticed at first. Later symptoms may include muscle weakness and twitching, slurred speech, impaired thinking and reasoning, and mental disorders. The life expectancy for a person with LOTS is not known because this condition has only recently been recognized. Depending on the severity of the symptoms, the person may live as long as someone who does not have Tay-Sachs disease. How is Tay-Sachs disease diagnosed?A physical examination and a blood test to measure the level of hex A is used to diagnose and screen for Tay-Sachs disease. A positive Tay-Sachs screen blood test may need to be confirmed with other genetic tests. How is it treated?Treatment for Tay-Sachs disease focuses on controlling symptoms and preparing for the course of the disease. There is no cure for Tay-Sachs disease. Additional personal and family support measures may be needed as the disease progresses. How can Tay-Sachs disease be prevented?If either you or your partner is Ashkenazi Jew or of French-Canadian or Cajun descent or has a family history of Tay-Sachs disease, that person needs to be tested for the Tay-Sachs trait. If that person tests positive, the partner also needs to be tested. If both of you test positive, you should consider genetic counseling before having children. Frequently Asked Questions
SymptomsA 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 an illustration 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:
At 6 to 10 months, you may notice:
10 months and olderAs 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 diseaseSymptoms 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:
Exams and TestsIf 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. 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 on a blood sample collected from the placenta during chorionic villus sampling or on a sample of amniotic fluid collected during amniocentesis. For more information, see the medical tests 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 carriersKnowing whether you are a carrier of Tay-Sachs disease is important, because Tay-Sachs is an autosomal recessive disease. If you are a carrier, you have the Tay-Sachs trait but not the disease. You have one chromosome that produces hexosaminidase A and one that does not produce this enzyme. Your body probably makes about 50% of the normal level of hex A, which prevents you from getting the disease; however, you can pass the trait on to your children. If both you and your spouse 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:1
Recently, one study compared testing for hexosaminidase A with testing DNA directly for Tay-Sachs disease. Evidence indicates that DNA testing is the most cost-effective and efficient approach to carrier screening.2 Treatment OverviewTreatment is aimed at controlling symptoms, such as medication for seizures. There is no cure for Tay-Sachs disease. Treatment for classical or infantile Tay-Sachs diseaseIf your baby has Tay-Sachs disease, other support measures may be needed as the disease progresses, such as:
Treatment for late-onset Tay-Sachs diseaseTreatment for late-onset Tay-Sachs disease (LOTS) also focuses on controlling symptoms. Since this form of the disease was recognized only recently, not much is known about its course. However, it is known that the nervous system effects get progressively worse over time. The treatment you receive, such as medication 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 AboutSome animal tests have been done using the enzyme sialidase to reduce the accumulation of gangliosides, which build up in the brain and nerve cells.3 Another study was done using gene transfer, or putting the hex A enzyme in the brain so it will move to the rest of the body where it is needed.4 Although this is preliminary, these studies may offer future hope for Tay-Sachs disease treatment. Talk to your health professional for more information. Home TreatmentHome 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 health professional about:
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 health professional 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 diseaseIf 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 health professional 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. Other Places To Get HelpOnline Resource
Organizations
Related InformationReferences
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