A Novel Mutation in MARS in a Patient with Charcot-Marie-Tooth Disease, Axonal, Type 2U with Congenital Onset

J Neuromuscul Dis. 2019;6(3):333-339. doi: 10.3233/JND-190404.


Charcot-Marie-Tooth disease is a phenotypically and genetically heterogeneous group of disorders affecting both motor and sensory neurons. Exome sequencing has driven discovery of genes responsible for Charcot-Marie-Tooth disease with more than 70 genes now associated with this neuromuscular disease. The MARS gene was recently reported as the cause of Charcot-Marie-Tooth 2U, a slowly progressive axonal sensorimotor polyneuropathy with adult-onset reported in six patients. We report here a patient with a progressive, early childhood-onset, motor-predominant form of Charcot-Marie-Tooth disease. Exome sequencing identified a novel MARS variant (c.1189G>A; p.Ala397Thr) that was not present in her unaffected mother; her unaffected father was unavailable. Further studies using structural modeling and a yeast humanization assay support pathogenicity of the variant. Our study expands the phenotype of Charcot-Marie-Tooth 2U, while highlighting the utility of functional assays to evaluate variant pathogenicity.

Keywords: CMT2U; Charcot-Marie-Tooth disease type 2U; MARS; early-onset neuropathy; exome sequencing.

Publication types

  • Case Reports

MeSH terms

  • Charcot-Marie-Tooth Disease / genetics*
  • Child
  • Female
  • Humans
  • Methionine-tRNA Ligase / genetics*
  • Mutation
  • Phenotype
  • Protein Structure, Tertiary


  • MARS1 protein, human
  • Methionine-tRNA Ligase