Definition:
Adult Onset Sandhoff Disease/GM2 Gangliosidosis is a group of inherited neurodegenerative diseases caused by a deficiency of the enzymes Hexosaminidase A (Hex-A) and Hexosaminidase B (Hex-B), which results in the accumulation of certain fats, gangliosides, in the brain. The bodies of individuals affected with Sandhoff are unable to break down GM2 gangliosides, hence the gangliosides build in the lysosomes.

Since a low level of functional Hex-A and Hex-B enzymes are found in adult cases, the symptoms of this disorder present later than they present with the two forms of Sandhoff Disease that are characterized by virtually no Hex-A and Hex-B enzymes. Therefore, the amount of Hex-A and Hex-B enzymes dictates the age of symptom onset and also the classification of the type of Sandhoff Disease.

Symptoms:
Symptoms of the disease begin in adolescence and include muscle weakness, tremors and slurred speech.  Leg cramps, particularly at night, and muscle twitching are also common symptoms. Although symptoms may vary from individual to individual, weakness in the trunk muscles is one symptom common to all affected with this disorder.  Dementia, which often occurs with other neurologic disabilities, is also a common symptom of this form of the disease.

Inheritance Pattern:
Adult Onset Sandhoff Disease/GM2 Gangliosidosis is an autosomal recessive disorder.

Diagnosis and Testing:
Adult Onset Sandhoff Disease/GM2 Gangliosidosis is usually diagnosed by measuring Hexosaminidase A and B activity in the blood. The disease can also be detected in a liver tissue biopsy or an enzyme assay to determine whether abnormally low levels of the enzyme are present.

Individuals at risk of this disease can undergo genetic screening to determine their carrier status before they decide to have children.  Some medical professionals highly recommend DNA testing for those parents who do not have a family history of Sandhoff Disease. More than 95% of the families that have children with this disorder had no known prior family history of the condition, due to the gene mutation’s silent or recessive nature and to its ability to pass from one generation to another without recognition. Genetic counseling is recommended for those who have the mutation.

Life Expectancy:
Life expectancy of patients with Adult Onset Sandhoff Disease is likely not affected or reduced from normal life expectancy.  The uncertainty of the disorder’s progression along with its physical and psychological effects may adversely affect the social skills and academic performance of those who have this form of the disease.  

Treatment:
There is no treatment for Adult Onset Sandhoff Disease.  Preventive genetic counseling is highly encouraged. It is the hope that one day gene therapy will prove to be for a cure for Sandhoff Disease.

Patient Groups:
Sandhoff Disease
259 Majorca Road
St. Augustine, FL 32080
http://www.sandhoffdisease.webs.com/
tel: (904) 662-1840
Gina Watkins
gmwatkins74@yahoo.com