Tay-Sachs Disease

(TSD)

Definition

Tay-Sachs disease (TSD) is a fatal genetic disorder. It occurs when a fatty substance builds up in the brain. This causes progressive destruction of the brain. There are three forms:
  • Infantile-onset
  • Juvenile-onset
  • Adult-onset
Given the best of care, all children with the infantile form die by the age of five.

Causes

TSD is caused by the absence of an enzyme. This enzyme is needed to break down a fatty substance called GM2 (ganglioside). As a result, GM2 builds up. The build up in the brain causes damage.
TSD occurs when both parent pass on the faulty genes. A person can have just one copy of the faulty gene. In this case, there are no symptoms. The person is called a carrier.
Genetic Material
Chromosome DNA
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Risk Factors

Factors that increase your chance for TSD include:
  • Having parents who are carriers of the TSD gene
  • Race: Eastern European (Ashkenazi) Jewish descent
  • TSD is also frequently found in French Canadian and Cajun populations

Symptoms

Babies with TSD may seem to develop normally until about 4-5 months of age. There is then an arrest of development. Symptoms begin to occur. Symptoms may include:
  • Floppy body position
  • Shrill cry
  • Decreased eye contact
  • Increased startle reaction
  • Loss of motor skills
  • Enlarged head
  • Vision loss or blindness
  • Deafness
  • Difficulty swallowing
  • Muscular difficulties (eg, spastic muscles, weakness or paralysis)
  • Intellectual disability
  • Seizures
In some cases, the symptoms do not begin until age 2-5 years old. The condition progresses slowly, but most children with Tay-Sachs disease do not live beyond age 15 years. Symptoms may include:
  • Loss of the ability to speak
  • Developmental delay and intellectual disability
  • Loss of bowel control
  • Sleep problems
  • Movement disorder (eg, gait disturbance, muscle weakness, loss of the ability to walk)
  • Tremor
  • Slurred speech
  • Psychiatric problems

Diagnosis

The doctor will ask about your child's symptoms and medical history. A physical exam will be done. The doctor may examine your child's eyes to look for a cherry red spot on the retina. Your doctor may also order:
  • Blood test—to measure hexosaminidase A activity

Treatment

There is presently no treatment for TSD. However, research is ongoing.

Prevention

There are no known ways to prevent Tay-Sachs disease. If you are a carrier of the gene that causes TSD, you can talk to a genetic counselor before deciding to have children. Prenatal testing during the first trimester is available.

RESOURCES

Genetic Alliance http://www.geneticalliance.org/

March of Dimes Birth Defects Foundation http://www.marchofdimes.com/

National Tay-Sachs & Allied Diseases Association, Inc. http://www.ntsad.org/

CANADIAN RESOURCES

About Kids Health http://www.aboutkidshealth.ca/

Caring for Kids The Canadian Paediatric Society http://www.caringforkids.cps.ca/

References

Filho JAF, Shapiro BE. Tay-Sachs disease. Arch Neurol . 2004; 61:1466-1468.

Matalon R, Michals-Matalon K, Schiffmann R. GM2 gangliosidoses. MedLink website. Available at: http://www.medlink.com . Accessed September 30, 2011.

National Tay-Sachs & Allied Diseases Association, Inc. website. Available at: http://www.ntsad.org .

Nelson Textbook of Pediatrics . 18th ed. WB Saunders; 2007.

Tay-Sachs disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/ . Updated July 20, 2011. Accessed September 30, 2011.

Tay-Sachs disease information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm . Accessed September 30, 2011.

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