Moreover, apoptotic and cell death proteins are dysregulated in skeletal muscle from SMA patients and mouse models (Cifuentes-Diaz et al., 2001; Shafey et al., 2005; Dachs et al., 2011; Mutsaers et al., 2011; Martínez-Hernández et al., 2013; Armbruster et al., 2016). Here, PROS1 is linked to proximal spinal muscular atrophy.