Gangliosidosis-1 (GM-1) - Causes

Gangliosidosis-1 (GM-1) disease is caused by the absence or significantly reduced level of a vital Glossary Link enzyme called beta-galactosidase (GLB1). Without GLB1, a fatty substance or lipid called GM-1 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation, also called “ substrate,” causes progressive damage to the cells.

The Juvenile and Late Onset forms of GM-1 occur when the mutations allow the GLB1 enzyme to function a little bit. Just a small increase in GLB1 activity is enough to delay the onset and slow the progression of symptoms.

Inheritance

GM-1 is an Glossary Link autosomal recessive genetic disorder. Both parents must be a carrier for children to be at risk. There is a 25% chance with each pregnancy the child will be affected.
GM-1 ‘breeds true’ in a family. If one child is diagnosed with infantile GM-1 the other children are only at risk for the infantile form. One set of parents could not have children with both the infantile and juvenile forms of the disease.