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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.
Chromosome
Chromosomes are structures found in the center (nucleus) of cells that carry long pieces of DNA. DNA is the material that holds genes. It is the bu...
Anyone can be a carrier of Tay-Sachs. But, the disease is most common among the Ashkenazi Jewish population. One in every 27 members of the population 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:
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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.
ImageRead Article Now Book Mark Article - Slow growth and delayed mental and social skills
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Dementia
(loss of brain function)
Dementia
Dementia is a loss of brain function that occurs with certain diseases. It affects memory, thinking, language, judgment, and behavior.
ImageRead Article Now Book Mark Article - Increased startle reaction
- Irritability
- Listlessness
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Seizures
Seizures
A seizure is the physical findings or changes in behavior that occur after an episode of abnormal electrical activity in the brain. The term "seizure...
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Exams and Tests
The health care provider will examine the baby and ask about your family history. Tests that may be done are:
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Enzyme
exam of blood or body tissue for hexosaminidase levels
Enzyme
Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For example, they can help break down the foods we eat ...
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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 at the center ...
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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.
- Cure Tay Sachs Foundation -- www.curetay-sachs.org
- National Tay-Sachs and Allied Diseases Association -- www.ntsad.org
- Genetic Alliance -- www.geneticalliance.org
- March of Dimes -- www.marchofdimes.org
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.
Spasticity
Spasticity is stiff or rigid muscles. It may also be called unusual tightness or increased muscle tone. Reflexes (for example, a knee-jerk reflex) ...
When to Contact a Medical Professional
Go to the emergency room or call the local emergency number (such as 911) if:
- Your child has a seizure of unknown cause
- The seizure is different from previous seizures
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The child has
difficulty breathing
Difficulty breathing
Breathing difficulty may involve:Difficult breathingUncomfortable breathingFeeling like you are not getting enough air
ImageRead Article Now Book Mark Article - The seizure lasts longer than 2 to 3 minutes
Call for an appointment with your provider if your child has other noticeable behavioral changes.
Prevention
There is no known way to prevent this disorder. 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.
References
Kwon JM. Neurodegenerative disorders of childhood. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 599.
Nussbaum RL, McInnes RR, Willard HF. The molecular, biochemical, and cellular basis of genetic disease. In: Nussbaum RL, McInnes RR, Willard HF, eds. Thompson and Thompson Genetics in Medicine . 8th ed. Philadelphia, PA: Elsevier; 2016:chap 12.
Wapner RJ. Prenatal diagnosis of congenital disorders. In: Creasy RK, Resnik R, Iams JD, Lockwood CJ, Moore TR, Greene MF, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice . 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 30.
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Central nervous system and peripheral nervous system - illustration
The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Central nervous system and peripheral nervous system
illustration
Review Date: 10/30/2016
Reviewed By: Anna C. Edens Hurst, MD, MS, Assistant Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
