Hereditary Spastic Paraplegia (HSP)
Description
Hereditary Spastic Paraplegia (HSP) is a group of inherited neurological disorders characterized by progressive spasticity, or stiffness, in the legs. This stiffness is caused by damage to the nerve pathways in the spinal cord that control movement. People with HSP may also experience weakness in their legs, difficulty walking, and other symptoms. HSP is a rare disorder, affecting about 1 in 10,000 people. There is no cure for HSP, but there are treatments that can help manage the symptoms and improve quality of life.
Genes Involved
There are over 80 genes that have been linked to HSP. Some of the most common genes include:
- SPG3A (ATP1A3)
- SPG4 (SPAST)
- SPG7 (PARAL1)
- SPG11 (KIAA1840)
- SPG20 (ZFYVE26)
The specific gene that is mutated can affect the type of HSP and the severity of the symptoms.
Recognizing the Signs and Symptoms
The most common symptom of HSP is spasticity, which is characterized by muscle stiffness and tightness. This spasticity can make it difficult to walk, move the legs, or perform other activities. Other symptoms of HSP may include:
- Weakness in the legs
- Difficulty walking or maintaining balance
- Foot drop, where the foot hangs down and drags
- Muscle cramps
- Bladder and bowel control problems
- Fatigue
- Pain in the legs
- Difficulty with fine motor skills, such as writing or buttoning clothes
The severity of HSP symptoms can vary widely from person to person. Some people may experience only mild symptoms, while others may be severely disabled. The symptoms of HSP typically worsen over time.
Causes
HSP is caused by mutations in genes that are involved in the development or function of the nervous system. These mutations can be inherited from a parent or can occur spontaneously. In most cases, the cause of HSP is unknown.
Inheritance/recurrence risk
HSP is usually inherited in an autosomal recessive pattern, which means that both parents must carry the mutated gene for a child to inherit the disorder. If both parents carry the gene, there is a 25% chance that their child will inherit HSP. There is also a 50% chance that a child will be a carrier of the gene, meaning they do not have the disorder but can pass the gene on to their children. In some cases, HSP can be inherited in an autosomal dominant pattern, which means that a child only needs to inherit one copy of the mutated gene to have the disorder. If one parent carries the mutated gene, there is a 50% chance that their child will inherit HSP.
