SMN1 and amyotrophic lateral sclerosis: Several genes in ALS are known to cause many other neurodegenerative diseases, such as alsin with primary lateral sclerosis (PLS), and infantile onset ascending hereditary spastic paralysis (IAHSP), senataxin with SCAR1 or AOA2, spatacsin with HSP, VAPB with SMA, FIG 4 with CMT type 4 J, OPTN with primary open angle glaucoma.