MAPK8 and proximal spinal muscular atrophy: The JNK signaling pathway has been reported to affect not only motor neuron diseases – such as SBMA, amyotrophic lateral sclerosis and spinal muscular atrophy – but also Huntington's disease, Alzheimer's disease, schizophrenia and many other neurological disorders (Mehan et al., 2011; Perrin et al., 2009; Schellino et al., 2019; Winchester et al., 2012).