GM1 gangliosidosis type 2
- Gangliosidosis generalized GM1 juvenile type
- Gangliosidosis generalized GM1 type 2
- Juvenile GM1 gangliosidosis
- Late-infantile GM1 gangliosidosis
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Classic infantile (type 1) GM1 gangliosidosis is the most severe type, with onset shortly after birth (usually within 6 months of age). Affected infants typically appear normal until onset, but developmental regression (loss of acquired milestones) eventually occurs. Signs and symptoms may include neurodegeneration, seizures, liver and spleen enlargement, coarsening of facial features, skeletal irregularities, joint stiffness, a distended abdomen, muscle weakness, an exaggerated startle response to sound, and problems with gait (manner of walking). About half of individuals with this type develop cherry-red spots in the eye. Children may become deaf and blind by one year of age. Affected children typically do not live past 2 years of age.
Signs and symptoms of juvenile (type 2) GM1 gangliosidosis, considered an intermediate form of the condition, may begin between the ages of 1 and 5. Features include include ataxia, seizures, dementia, and difficulties with speech. This type progresses more slowly than type 1, but still causes decreased life expectancy (around mid-childhood or early adulthood).
Adult (type 3) GM1 ganglioosidosis may cause signs and symptoms to develop anywhere between the ages of 3 and 30. Affected individuals may have muscle atrophy, corneal clouding and dystonia. Non-cancerous skin blemishes may develop on the lower part of the trunk of the body. Adult GM1 is usually less severe and progresses more slowly than other forms of the condition.
Mutations in the GLB1 gene may decrease or eliminate the activity of the β-galactosidase enzyme, which means that the GM1 ganglioside cannot be broken down. As a result, it accumulates to toxic levels in tissues and organs, particularly in the brain. This accumulation then leads to the destruction of nerve cells in the brain, which causes the features of the condition.
In general, individuals with higher enzyme activity levels usually have milder signs and symptoms than those with lower activity levels because they have less accumulation of GM1 ganglioside within the body.
It is important to note that GM1 gangliosidosis is type-specific within families. This means that individuals with a family history of the condition are generally only at increased risk for the specific type of GM1 gangliosidosis in the family.
Bone marrow transplantation was reportedly successful in an individual with infantile/juvenile GM1 gangliosidosis; however, no long-term benefit was reported. Presymptomatic cord-blood hematopoietic stem-cell transplantation has been advocated by some as a possible treatment due to its success in other lysosomal storage disorders. Active research in the areas of enzyme replacement and gene therapy for the condition is ongoing but has not yet advanced to human trials.
Neurologic and orthopedic sequelae may prevent adequate physical activity, but affected individuals may benefit from physical and occupational therapy.
- NINDS Gangliosidoses Information Page. National Institute of Neurological Disorders and Stroke (NINDS). October 2011; http://www.ninds.nih.gov/disorders/gangliosidoses/Gangliosidoses.htm. Accessed 4/3/2012.
- GM1 gangliosidosis. Genetics Home Reference. July 2010; http://ghr.nlm.nih.gov/condition/gm1-gangliosidosis. Accessed 4/3/2012.
- Tegay D. GM1 Gangliosidosis. eMedicine. March 29, 2012; http://emedicine.medscape.com/article/951637-overview. Accessed 4/3/2012.
- About Gangliosidosis-1 (GM-1). National Tay-Sahs and Allied Diseases Association, Inc.. http://www.ntsad.org/index.php/the-diseases/gm-1. Accessed 4/3/2012.
- David H. Tegay. GM1 Gangliosidosis. Medscape Reference. March 29, 2012; http://emedicine.medscape.com/article/951637-overview. Accessed 8/6/2012.
- GM1 Gangliosidosis - Infantile. Hide & Seek Foundation for Lysosomal Disease Research. http://www.hideandseek.org/Diseases.html. Accessed 4/3/2012.