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Spastic paraplegia type 7
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Spastic paraplegia type 7

Spastic paraplegia type 7 is a genetic disorder that causes progressive muscle stiffness and weakness, primarily affecting the brain and spinal cord.

Overview

Spastic paraplegia type 7 (SPG7) is one of more than 80 types of hereditary spastic paraplegias. These disorders affect neurons that extend down the spinal cord, which are critical for muscle movement and sensation. SPG7 can present as either a pure form (involving only lower limb spasticity) or a complex form (involving more widespread nervous system issues).

Symptoms

While symptoms vary greatly, they typically become noticeable in adulthood. Common features include:

  • Muscle issues: Stiffness (spasticity), weakness, and muscle wasting (amyotrophy).
  • Movement abnormalities: Ataxia (lack of coordination), parkinsonism, and involuntary eye movements (nystagmus).
  • Neurological/Sensory: Speech difficulties (dysarthria), difficulty swallowing (dysphagia), exaggerated reflexes in the arms, and sensory or motor neuropathy (numbness, tingling, or pain).
  • Physical features: Abnormal curvature of the spine and high-arched feet.

Causes

SPG7 is caused by mutations in the SPG7 gene, which provides instructions for producing a protein called paraplegin. Paraplegin is located in the mitochondria (the energy-producing centers of cells) and forms a complex called the m-AAA protease. This enzyme is responsible for assembling ribosomes and removing nonfunctional proteins. When the SPG7 gene is mutated, nonfunctional m-AAA proteases lead to a build-up of unusable proteins in nerve cell mitochondria, causing cell swelling and impaired signaling.

Inheritance

In most cases, spastic paraplegia type 7 is inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell have mutations. Parents of an affected individual typically do not show symptoms. In rare cases, the condition can be inherited in an autosomal dominant pattern.

Frequently Asked Questions

Early intervention is key; starting physiotherapy in the late teens or early twenties—when symptoms first appear—can help maintain mobility. Focus on low‑impact aerobic activities (walking, cycling), stretching for spasticity, and strength training for the lower limbs using resistance bands or light weights. Gait training with a physiotherapist and the use of ankle‑foot orthoses can improve walking endurance and reduce fall risk. How can clinicians distinguish between the pure and complex forms of SPG7 in a patient presenting with lower‑limb weakness?::The pure form typically shows isolated spasticity and weakness in the legs with normal upper‑limb function and no sensory loss. In contrast, the complex form includes additional features such as ataxia, dysarthria, dysphagia, or sensory neuropathy. A detailed neurological exam, nerve conduction studies, and brain MRI can help identify these extra manifestations and guide classification. What are the most common complications of mitochondrial dysfunction in SPG7, and how should they be monitored over time?::Patients are at risk for optic atrophy, hearing loss, and cardiac arrhythmias due to impaired mitochondrial energy production. Regular ophthalmologic exams, audiometry, and ECGs every 1–2 years are recommended. Monitoring for respiratory muscle weakness with pulmonary function tests can catch early decline, especially in advanced disease. Are there any clinical trials or emerging therapies targeting paraplegin or mitochondrial function for SPG7 patients?::Several research groups are investigating small‑molecule chaperones that stabilize paraplegin or enhance mitochondrial protease activity. Gene‑replacement therapy using adeno‑associated virus vectors is also in preclinical stages. Patients can search clinicaltrials.gov for ongoing studies or contact a neuromuscular specialty center for trial eligibility.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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