Tay-Sachs disease

GM2 gangliosidosis - Tay-Sachs; Lysosomal storage disease - Tay-Sachs disease

Tay-Sachs disease is a life-threatening disease of the nervous system passed down through families.

Causes

Tay-Sachs disease occurs when the body lacks hexosaminidase A. This is a protein that helps break down a group of chemicals found in nerve tissue called gangliosides. Without this protein, gangliosides, particularly ganglioside GM2, build up in cells, often nerve cells in the brain.

Tay-Sachs disease is caused by a defective gene on chromosome 15. When both parents carry the defective Tay-Sachs gene, a child has a 25% chance of developing the disease. The child must receive two copies of the defective gene, one from each parent, in order to become sick. If only one parent passes the defective gene to the child, the child is called a carrier. They will not be sick, but may pass the disease to their own children.

Anyone can be a carrier of the Tay-Sachs gene. But, the disease is most common among people with Ashkenazi Jewish ancestry, where 1 in every 27 people carries the Tay-Sachs gene.

Tay-Sachs is divided into infantile, juvenile, and adult forms, depending on the symptoms and when they first appear. Most people with Tay-Sachs have the infantile form. In this form, the nerve damage usually begins while the baby is still in the womb. Symptoms usually appear when the child is 3 to 6 months old. The disease tends to get worse very quickly, and the child usually dies by age 4 or 5.

Late-onset Tay-Sachs disease, which affects adults, is very rare.

Symptoms

Symptoms may include any of the following:

Deafness
Deafness
Hearing loss is being partly or totally unable to hear sound in one or both ears.
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Decreased eye contact, blindness
Blindness
Blindness is a lack of vision. It may also refer to a loss of vision that cannot be corrected with glasses or contact lenses. Partial blindness mean...
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Decreased muscle tone (loss of muscle strength), loss of motor skills, paralysis
Decreased muscle tone
Hypotonia means decreased muscle tone.
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Slow growth and delayed mental and social skills
Dementia (loss of brain function)
Dementia
Dementia is a loss of brain function that occurs with certain diseases. It affects one or more brain functions such as memory, thinking, language, j...
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Increased startle reaction
Irritability
Listlessness
Seizures
Seizures
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
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Exams and Tests

The health care provider will examine your baby and ask about your family history. Tests that may be done are:

Enzyme exam of blood or body tissue for hexosaminidase levels
Enzyme
Enzymes are complex proteins that cause a specific chemical change. For example, they can help break down the foods we eat so the body can use them....

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Eye exam (reveals a cherry-red spot in the macula)
Macula
When an eye is looking directly at an object, light rays from that object are focused on the macula lutea. This is a yellow oval spot ("lutea" is La...
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Genetic testing

Treatment

There is no treatment for Tay-Sachs disease itself, only ways to make the person more comfortable.

Support Groups

The stress of illness may be eased by joining support groups whose members share common experiences and problems. The following groups can provide more information on Tay-Sachs disease:

National Organization for Rare Disorders -- rarediseases.org/rare-diseases/tay-sachs-disease
National Tay-Sachs and Allied Diseases Association -- www.ntsad.org
NLM Genetics Home Reference -- ghr.nlm.nih.gov/condition/tay-sachs-disease

Outlook (Prognosis)

Children with this disease have symptoms that get worse over time. They usually die by age 4 or 5.

Possible Complications

Symptoms appear during the first 3 to 10 months of life and progress to spasticity, seizures, and loss of all voluntary movements.

When to Contact a Medical Professional

Go to the emergency room or call 911 or the local emergency number if:

Your child has a seizure of unknown cause
The seizure is different from previous seizures
The child has difficulty breathing
Difficulty breathing
Breathing difficulty may involve:Difficult breathing Uncomfortable breathingFeeling like you are not getting enough air
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The seizure lasts longer than 2 to 3 minutes

Contact your provider for an appointment if your child has other noticeable behavioral changes.

Prevention

There is no known way to prevent this disorder once someone is born. Genetic testing can detect if you are a carrier of the gene for this disorder. If you or your partner is from an at-risk population, you may wish to seek genetic counseling before starting a family.

If you are already pregnant, testing the amniotic fluid can diagnose Tay-Sachs disease in the womb.

Open References

References

Kwon JM. Neurodegenerative disorders of childhood. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 617.

Nussbaum RL, McInnes RR, Willard HF. The molecular, biochemical, and cellular basis of genetic disease. In: Nussbaum RL, McInnes RR, Willard HF, eds. Thompson & Thompson Genetics in Medicine. 8th ed. Philadelphia, PA: Elsevier; 2016:chap 12.

Wapner RJ, Dugoff L. Prenatal diagnosis of congenital disorders. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 32.

Central nervous system and peripheral nervous system - illustration
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes nerves outside the brain and spinal cord.
Central nervous system and peripheral nervous system
illustration
Autosomal recessive - illustration
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop. For a child born to a couple who both carry the gene (but the parents themselves do not have signs of disease), the expected outcome for each pregnancy is: a 50% chance that the child is born with one normal and one abnormal gene (carrier, without disease), a 25% chance that the child is born with two normal genes (normal), and a 25% chance that the child is born with two abnormal genes (at risk for the disease). Note: These outcomes do not mean that the children will definitely be carriers or be severely affected.
Autosomal recessive
illustration

Central nervous system and peripheral nervous system - illustration
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes nerves outside the brain and spinal cord.
Central nervous system and peripheral nervous system
illustration
Autosomal recessive - illustration
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop. For a child born to a couple who both carry the gene (but the parents themselves do not have signs of disease), the expected outcome for each pregnancy is: a 50% chance that the child is born with one normal and one abnormal gene (carrier, without disease), a 25% chance that the child is born with two normal genes (normal), and a 25% chance that the child is born with two abnormal genes (at risk for the disease). Note: These outcomes do not mean that the children will definitely be carriers or be severely affected.
Autosomal recessive
illustration

A Closer Look

Talking to your MD

Self Care

Tests for Tay-Sachs disease

Review Date: 10/13/2022

Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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Health Library

Tay-Sachs disease

Causes

Chromosome

Symptoms

Deafness

Blindness

Decreased muscle tone

Dementia

Seizures

Exams and Tests

Enzyme

Macula

Treatment

Support Groups

Support groups

Outlook (Prognosis)

Possible Complications

Spasticity

When to Contact a Medical Professional

Difficulty breathing

Prevention

Genetic counseling