Although the majority of studies have focused on BDNF instead NT-4/5, probably because NT-4/5 was discovered later and both factors use the same receptor, Harandi et al. in 2014 [65] demonstrated the presence of NT-4/5 mRNA in extraocular muscles obtained from SOD1 mice, a mouse model of amyotrophic lateral sclerosis (ALS). Here, BDNF is linked to amyotrophic lateral sclerosis.