Nervous System Home > Sandhoff Disease
The prognosis for individuals with Sandhoff disease is poor. Death usually occurs by age 3, and is generally caused by respiratory infections.
Mutations in the HEXB gene cause Sandhoff disease. The HEXB gene is located on chromosome number 5.
The HEXB gene provides instructions for making a protein that is part of two critical enzymes in the nervous system. These enzymes, beta-hexosaminidase A and beta-hexosaminidase B, function in nerve cells to break down fatty substances, complex sugars, and molecules that are linked to sugars. In particular, beta-hexosaminidase A breaks down a fatty compound called GM2 ganglioside.
Mutations in the HEXB gene disrupt the activity of these enzymes, preventing the breakdown of GM2 ganglioside and other molecules. As a result, these compounds can accumulate to toxic levels within cells. Progressive damage caused by the buildup of GM2 ganglioside leads to the destruction of nerve cells, which causes the signs and symptoms of Sandhoff disease.