Novel motor phenotypes in patients with VRK1 mutations without pontocerebellar hypoplasia

OBJECTIVE: To describe the phenotypes in 2 families with vaccinia-related kinase 1 (VRK1) mutations including one novel VRK1 mutation. METHODS: VRK1 mutations were found by whole exome sequencing in patients presenting with motor neuron disorders. RESULTS: We identified pathogenic mutations in the VRK1 gene in the affected members of 2 families. In family 1, compound heterozygous mutations were identified in VRK1, c.356A>G; p.H119R, and c.1072C>T; p.R358*, in 2 siblings with adult onset distal spinal muscular atrophy (SMA). In family 2, a novel VRK1 mutation, c.403G>A; p.G135R and c.583T>G; p.L195V, were identified in a child with motor neuron disease. CONCLUSIONS: VRK1 mutations can produce adult-onset SMA and motor neuron disease in children without pontocerebellar hypoplasia.