SMN1 and amyotrophic lateral sclerosis: It is remarkable that, in contrast to γ-MNs being largely spared in murine models of both ALS and SMA, α-MNs and proprioceptive fibers seem to be mostly vulnerable (Lalancette-Hebert et al. 2016; Powis and Gillingwater 2016; Falgairolle and O’Donovan 2020).