Spastic paraplegia-31 (SPG31) is an autosomal dominant neurologic disorder characterized primarily by spasticity of the lower limbs, resulting in gait abnormalities and muscle weakness. There is a bimodal age at onset with a peak in the second and fourth decades of life. Most affected individuals have a 'pure' form of the disorder with gait difficulties and hyperreflexia of the lower limbs. However, there is phenotypic heterogeneity, and some patients have a 'complex' form of the disorder with additional signs and symptoms, such as peripheral neuropathy, cerebellar ataxia, postural tremor, or urinary symptoms. The disorder is slowly progressive, and there is intrafamilial variability and incomplete penetrance (summary by Goizet et al., 2011 and Toft et al., 2019).
For a general phenotypic description and a discussion of genetic heterogeneity of autosomal dominant spastic paraplegia, see SPG3A (182600). [from
OMIM]