Tay-Sachs disease

Definition 
Tay-Sachs disease is a familial disorder found predominantly in Ashkenazi Jewish families that results in early death.

Causes, incidence, and risk factors 

Tay-Sachs disease is caused by a deficiency of hexosaminidase, an enzyme that is important in the metabolism of gangliosides (a type of chemical substance found in nerve tissue).

These gangliosides, particularly ganglioside GM2, then accumulate in the brain, causing neurological deterioration. Tay-Sachs disease is inherited as a recessive gene, and 1 in 25 members of the Ashkenazi Jewish population carries the gene.

Tay-Sachs has been classified into infantile, juvenile, and adult forms, depending on the type of symptoms and when they first appear. The majority of people with Tay-Sachs have infantile forms.

Symptoms generally begin to appear when the child is 3 to 6 months old. The disease tends to progress rapidly, and the child usually dies by the age of 4 or 5 years.

Symptoms  

     
  • Loss of motor skills  
  • Increased startle reaction  
  • Decreased eye contact, blindness  
  • Deafness  
  • Dementia  
  • Listlessness  
  • Irritability  
  • Seizures  
  • Paralysis  
  • Decreased muscle tone (loss of muscle strength)  
  • Muscle function loss  
  • Delayed mental and social skills  
  • Slow growth

Signs and tests 

     
  • Family history  
  • Physical examination  
  • Enzyme analysis of blood or body tissue for hexosaminidase levels  
  • Eye examination (reveals a cherry-red spot in the macula)

Treatment  

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

Support Groups 
The stress of illness can often be helped by joining support groups where members share common experiences and problems. See Tay-Sachs - support group.

Expectations (prognosis) 
Children affected with this disease have progressive symptoms and usually die by 4 to 5 years of age.

Complications 
Note: Symptoms appear during the first 3 to 10 months of life and progress to spasticity, seizures, and loss of all voluntary movements, eventually causing death by the time the child is 4 to 5 years old.

Calling your health care provider 

Go to the emergency room or call the local emergency number (such as 911) if your child has a seizure of unknown cause, if the seizure is different from previous seizures, if the child has difficulty breathing, or if the seizure lasts longer than 2-3 minutes.

Call for an appointment with your health care provider if your child experiences a seizure lasting less than 2-3 minutes or has other noticeable behavioral changes.

Prevention 
There is no known way to prevent this disorder. However, genetic testing can detect carriers of the gene for this disorder and is recommended prior to conception for couples from at risk populations. Prenatal diagnosis is possible from amniotic fluid studies.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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