We aimed to systematically investigate the neuromuscular involvement of individuals with PRUNE mutations who may have a major spinal motor neuron involvement as part of the PRUNE-associated neurodegenerative phenotype. The complex neurological phenotypes associated with Prune mutations include microcephaly with brain abnormalities, spasticity, seizures, severe developmental delay and developmental regression. We used whole exome sequencing to identify the mutation and electrophysiological and muscle biopsy studies to evaluate the signs of spinal motor neuron involvement. The affected individuals carry homozygous PRUNE mutation (NM_021222.1, c.316G > A, p.D106N), showing the signs of spinal motor neuron involvement supported by electrophysiological and muscle biopsy findings and also persistent high creatine kinase levels. We confirm that individuals with PRUNE mutations may have a major spinal motor neuron involvement as part of the PRUNE-associated neurodegenerative phenotype. The PRUNE gene should be considered in all the individuals with non-5q spinal muscular atrophy. High creatine kinase values may be a part of PRUNE disease spectrum.

Keywords: PRUNE, creatine kinase, exome, hyperCkaemia, spinal motor neuron