The familial spastic paraplegias (FSP) are a group of heterogeneous inherited disorders characterized by progressive lower limb spasticity. The main feature of the disease is progressive weakening and stiffening of the legs, leading to a difficulty in walking or gait disturbances. This is especially true of pure familial spastic paraplegias. However, complex spastic paraplegias may involve other features, including dementia, ataxia, mental retardation, ichthyosis, peripheral neuropathy, distal amyotrophy, retinal changes, and/or hearing loss. The FSPs can be classified according to their mode of inheritance, and further, based on the exact gene defect. SPG3A, or Spastic Paraplegia 3A is an autosomal dominant form of the condition, that usually presents itself within the first or second decades of life. Patients with this form of FSP do not show involvement of any bladder or sensory complications.
The FSPs are diagnosed based on exclusion of all other diagnoses. Differential diagnoses include spinocerebellar ataxias, multiple sclerosis, motor neuron disease, and infectious spastic paraparesis. Although there is no specific treatment for the condition, management is possible by means of regular physical therapy. Medication may also help in reducing the spasticity. Prognosis for the condition also varies according to the severity of the condition. Generally, patients have a normal life expectancy, although the quality of life may be impacted for those with the severe form of the disease.
Mutations in SPG3A (ATL1; Atlastin GTPase 1) gene was identified to be associated with autosomal dominant form of spastic paraplegia. Mutations in SPAST (Spastin) gene are also known to cause autosomal dominant spastic paraplegia in patients with onset age lower than 10 years.