What is Sandhoff Disease from a medical perspective
What is Sandhoff Disease?
Sandhoff disease is a rare, genetic, lipid storage disorder resulting in the
progressive deterioration of the central nervous system. It is caused by a
deficiency of the enzyme beta-hexosaminidase, which results in the
accumulation of certain fats (lipids) in the brain and other organs of the body.
Sandhoff disease is a severe form of Tay-Sachs disease--which is prevalent
primarily in people of Eastern European and Ashkenazi Jewish descent--but it
is not limited to any ethnic group. Onset of the disorder usually occurs at 6
months of age. Neurological symptoms may include motor weakness, startle
reaction to sound, early blindness, progressive mental and motor
deterioration, macrocephaly (an abnormally enlarged head), cherry-red spots
in the eyes, seizures, and myoclonus (shock-like contractions of a muscle).
Other symptoms may include frequent respiratory infections, doll-like facial
appearance, and an enlarged liver and spleen.
Is there any treatment?
There is no specific treatment for Sandhoff disease. Supportive treatment
includes proper nutrition and hydration and keeping the airway open.
Anticonvulsants may initially control seizures.
What is the prognosis?
The prognosis for individuals with Sandhoff disease is poor. Death usually
occurs by age 3 and is generally caused by respiratory infections.
What research is being done?
The National Institute of Neurological Disorders and Stroke (NINDS), a
component of the National Institutes of Health (NIH), conducts research about
lipid storage diseases in laboratories at the NIH and also supports additional
research through grants to major medical institutions across the country
How is the disease transmitted?
When two unaffected carriers of the HexB gene mutation become parents,
then for each pregnancy:
There is a 1-in-4 (25%) chance that the child will inherit the regular HEXB gene
from each parent and will be completely free of the HEXB gene mutation and
will not be affected by SD.
There is a 2-in-4 (50%) chance that the child will inherit both a regular copy
and a faulty copy of the HEXB gene and be a carrier of the faulty gene,
unaffected by SD, just like his/her parents
There is a 1-in-4 (25%) chance that the child will inherit the faulty HEXB gene
from each parent. This child will be affected with Sandhoff disease.
Does it affect one's health to be a carrier of the HEXB genetic mutation?
No. Carriers of the HEXB gene mutation are completely unaffected by SD.
Is it possible to test to see if a person is a carrier of the faulty HEXB gene?
Yes. Although there is no cure or effective treatment for SD, genetics carrier
testing is available. Extensive genetics carrier testing for Tay-Sachs disease in
various regions of the world has lead to its virtual elimination in these areas.
If I do not have a family history of Sandhoff disease do I need to be tested?
Yes. Over 95% of couples with children affected by SD have no family history of
the disease because the HEXB gene mutation is silently passed down
through the generations. However, if there is a family history, then the risk is
much greater. People who have a known family history of SD should seek
further information through genetics counselling.