VRK1 and proximal spinal muscular atrophy: Variants in VRK1 have been segregated with motor neuron diseases including SMA phenotype, adult‐onset motor neuron disease, HMSN, and juvenile‐onset dHMN with or without pontocerebellar hypoplasia or microcephaly 7, 8, 9, 10, 11, 12, 13 (Table S1 and Fig. 4).