Reviewed January 2008
What is spastic paraplegia type 4?
Spastic paraplegia type 4 is part of a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by progressive muscle stiffness (spasticity) and the development of paralysis of the lower limbs (paraplegia). Hereditary spastic paraplegias are divided into two types: pure and complex. The pure types involve the lower limbs. The complex types involve the lower limbs and can also affect the upper limbs to a lesser degree; the structure or functioning of the brain; and the nerves connecting the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound (the peripheral nervous system). Spastic paraplegia type 4 is a pure hereditary spastic paraplegia.
Like all hereditary spastic paraplegias, spastic paraplegia type 4 involves spasticity of the leg muscles and muscle weakness. People with this condition can also experience exaggerated reflexes (hyperreflexia), ankle spasms, high-arched feet (pes cavus), and reduced bladder control. Spastic paraplegia type 4 generally affects nerve and muscle function in the lower half of the body only.
How common is spastic paraplegia type 4?
The prevalence of spastic paraplegia type 4 is estimated to be 2 to 6 in 100,000 people worldwide.
What genes are related to spastic paraplegia type 4?
Mutations in the SPAST gene cause spastic paraplegia type 4. The SPAST gene provides instructions for producing a protein called spastin. Spastin is found throughout the body, particularly in certain nerve cells (neurons). The spastin protein plays a role in the function of microtubules, which are rigid, hollow fibers that make up the cell's structural framework (the cytoskeleton). Microtubules are also involved in transporting cell components and facilitating cell division. Spastin likely helps restrict microtubule length and disassemble microtubule structures when they are no longer needed. Mutations in spastin impair the microtubules' ability to transport cell components, especially in nerve cells; researchers believe this contributes to the major signs and symptoms of spastic paraplegia type 4.
Read more about the SPAST gene.
How do people inherit spastic paraplegia type 4?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
In most cases, an affected person inherits the mutation from one affected parent. The remaining cases may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family.
Where can I find information about treatment for spastic paraplegia type 4?
These resources address the management of spastic paraplegia type 4 and may include treatment providers.
You might also find information on treatment of spastic paraplegia type 4 in
Educational resources and Patient support.
Where can I find additional information about spastic paraplegia type 4?
You may find the following resources about spastic paraplegia type 4 helpful. These materials are written for the general public.
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- Additional NIH Resources - National Institutes of Health
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You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for spastic paraplegia type 4?
- Autosomal Dominant Hereditary Spastic Paraplegia
- Hereditary Autosomal Dominant Spastic Paraplegia
- Hereditary Spastic Paraplegia
- spastic paraplegia 4
What if I still have specific questions about spastic paraplegia type 4?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding spastic paraplegia type 4?
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
healthcare professional.
See How can I find a genetics professional in my area? in the Handbook.