| A rare complex subtype of hereditary spastic paraplegia with characteristics of variable onset of slowly progressive lower limb spasticity and weakness and prominent cerebellar ataxia, associated with gait disturbances, dysarthria, increased deep tendon reflexes and extensor plantar responses. Additional features may include involuntary movements (such as clonus, tremor, fasciculations, chorea), decreased vibration sense, oculomotor abnormalities (for example nystagmus) and distal amyotrophy in the upper and lower limbs. Caused by homozygous mutation in the KIF1C gene on chromosome 17p13. |