| A very rare severe motor neuron disease with manifestation of progressive upper and lower motor neuron degeneration causing facial spasticity, dysarthria, and gait disorders with onset before 25 years of age. The disease is usually slowly progressive and some patients have been reported to become bedridden by 12 to 50 years of age. Mutations in the following genes have been found in patients ALS2 (2q33-q35), and rarely SIGMAR1 (9p13.3), SPG11 (15q13-q15) and FUS (16p11.2). |
