What is Sandhoff Disease?
Sandhoff Disease is an extremely rare inherited pathological condition which progressively destroys the nerve cells in the brain and the spinal cord. Sandhoff Disease is basically a lipid storage disorder and is caused by deficiency of beta-hexosaminidase enzyme resulting in excessive accumulation of lipids within the brain and various other vital organs of the body.
The onset of symptoms of Sandhoff Disease may begin as early as when the child is not even a year old. The neurological manifestations of Sandhoff Disease include gradual deterioration of the nervous system along with problems with motor function and control of movement and muscles. The baby may not even be able to see properly ass a result of Sandhoff Disease. Myoclonus is also one of the symptoms that are seen with Sandhoff Disease.
A baby born with Sandhoff Disease will have an abnormally large head and will be prone to frequent respiratory infections. Hepatomegaly and splenomegaly are also quite common in Sandhoff Disease. Sandhoff Disease is an autosomal recessive trait meaning that copies of the defective genes should be inherited from both parents in order to get Sandhoff Disease.
What are the Causes of Sandhoff Disease?
The root cause of Sandhoff Disease is mutations in the HEXB gene. The function of this gene is to control production of a protein which is a part of extremely important enzymes of the nervous system namely beta-hexosaminidase A and beta-hexosaminidase B.
These enzymes are situation in the lysosomes. These enzymes break down fatty substances and sugars. Mutations of the HEXB gene results in impairment of the production of the protein which forms a part of the enzymes beta-hexosaminidase A and beta-hexosaminidase B leading to the enzymes not functioning properly and unable to break down fatty substances and sugars.
As a result of this functional abnormality, fatty substances and sugars get accumulated in the body and attain toxic levels, specifically in the brain and the spinal cord which ultimately results in the development of Sandhoff Disease.
What are the Symptoms of Sandhoff Disease?
The initial presentation of symptoms of Sandhoff Disease begins by the time the baby is six months of age. It is at this time when their development starts to slow down significantly. There is also significant weakness of the muscles used for movement.
The weakness takes a drastic turn for the worse and the baby is unable to turn over, sit, or crawl. As Sandhoff Disease advances, the child may start experiencing seizures, hearing and ocular abnormalities. The child may also become intellectually disabled, and may also be become paralyzed.
Hepato and splenomegaly may also be noted in some cases of Sandhoff Disease. Additionally, the child will experience frequent respiratory infections and will also have some musculoskeletal abnormalities as a result of Sandhoff Disease.
How is Sandhoff Disease Diagnosed?
Based on the history and symptoms experienced by the child, the physician may suspect Sandhoff Disease and perform an enzyme assay to determine any abnormality in the hexosaminidase A and B enzymes. Child affected with Sandhoff Disease will clearly have abnormalities in the functioning of these enzymes which will virtually confirm the diagnosis of Sandhoff Disease. Genetic testing may also be done to check on mutations of the HEXB gene which will be positive in cases of Sandhoff Disease.
How is Sandhoff Disease Treated?
There is no clear cut cure for Sandhoff Disease. It is a progressive disorder with quite a poor prognosis and hence treatment is basically symptomatic and supportive. Conditions like respiratory infections and seizures can be controlled with medications.
Certain strengthening exercises may also help with the muscle weakness but ultimately the child succumbs to the disease by the age of maximum three years as a result of Sandhoff Disease. Genetic counseling is extremely important for people who have members of family with Sandhoff Disease.
What is the Prognosis of Sandhoff Disease?
The overall prognosis of Sandhoff Disease as stated above is extremely poor and the child ultimately succumbs mainly due to respiratory distress by the time he or she reaches age 3 as a result of Sandhoff Disease.