What is GM1 Gangliosidosis?
GM1 gangliosidosis is an inherited disorder that progressively damages the nerve cells in the brain and spinal cord. There are three main types of GM1 gangliosidosis that vary in severity:
Type I
Type I is the most severe form of this disorder, developing at around 6 months of age with an expected survival rate of early childhood. Symptoms can include:
- Slowing development and eventual regression
- Muscle weakness
- Cherry-red spot in eye
- Enlarged liver and spleen
- Skeletal abnormalities
- Seizures
- Intellectual disabilities
- Loss of vision
- “Coarse” facial features
- Enlarged gums
- Enlarged and weakened heart muscle
Type II
With Type II, children develop normally throughout early childhood, but they begin to develop symptoms anywhere between 18 months (late infantile) to 5 years (juvenile form). The symptoms are typically less severe than Type I, as they experience developmental regression, but they do not have cherry-red spots, enlarged organs, or “coarse” facial features. Life expectancy can range from mid-childhood to early adulthood.
Type III
Type III is the mildest form of GM1 gangliosidosis. Known as the adult or chronic form, Type III can develop at various ages, but mostly during a child’s teenage years. Symptoms can include involuntary muscle tensing, intellectual impairment, and abnormalities of the spinal bones. Life expectancy can vary amongst individuals.
How Do You Get GM1 Gangliosidosis?
GM1 gangliosidosis is caused by a mutation in the GLB1 gene that is inherited through an autosomal recessive pattern (the child inherits the gene mutation from both carrier parents). This gene mutation causes a deficiency of beta-galactosidase-1, an enzyme that breaks down sugar molecules.
How is GM1 Gangliosidosis Diagnosed?
This disorder can be diagnosed either through genetic testing of the GLB1 gene mutation or an enzyme analysis of the beta-galactosidase enzyme.
Is There a Treatment?
This disorder is currently untreatable, but symptoms can be managed to provide for a better quality of life. For instance, medications can be prescribed for seizures, and physical therapy can help with muscle weakness.
Helpful Resources
Genetic and Rare Diseases Information Center