Related Diseases
GM-1

Individuals affected by GM-1 gangliosidoses have very similar symptoms to those with Tay-Sachs or Sandhoff. GM-1 is caused by a deficiency of beta-galactosidase, which leads to an accumulation of gangliosides within specific tissues of the body. This disorder causes progressive neurological damage and is inherited in an autosomal recessive fashion. GM-1 has three forms: Classic Infantile, Juvenile and Late Onset or Chronic GM-1.

It is important to note that GM-1 ‘breeds true in a family,’ which means if a family has a child affected by Classic Infantile GM-1, then their other children will only be at risk for having Classic Infantile GM-1. One set of parents could not have a child affected by Classic Infantile and Juvenile or Late Onset GM-1.

Symptoms

The infantile form of GM-1 is the most common subtype and unfortunately also the most severe, with an onset shortly after birth. The symptoms of Infantile GM-1 include:

Patients with the Juvenile and Late Onset forms of GM-1 also experience problems with gait, have slurred speech and mental health issues. Only about half of all affected individuals will develop the cherry-red spot in the eye that is typically seen in Tay-Sachs patients.

The onset of Juvenile GM-1 is typically between the ages of 1 and 3 years. Symptoms include ataxia, seizures, dementia, and difficulties with speech. The age of onset for Late Onset GM-1 is more variable and can begin between ages 3 and 30, with symptoms that include muscle weakness, corneal clouding in some patients, and uncontrollable muscle twitching. Non-cancerous skin blemishes may also develop on the lower part of the trunk of the body. Late Onset GM-1 is usually less severe and progresses more slowly than the other forms of the disorder.

Causes

The GM-1 gangliosidoses are caused by a deficiency of the beta-galactosidase (GLB1) enzyme; the gene for this enzyme is located on chromosome 3. This enzyme breaks down carbohydrates into parts so they can be recycled.

Testing

Carrier testing and prenatal testing for GM-1 are available. Visit the Testing section of the site to learn more about carrier testing. For a list of laboratories capable of GM-1 carrier testing please visit www.genetests.org.

 

Additional Informational Links

The following online resources may be helpful in learning more about GM-1 disease: