Identification of novel pathogenic copy number variations in Charcot-Marie-Tooth disease

J Hum Genet. 2020 Mar;65(3):313-323. doi: 10.1038/s10038-019-0710-5. Epub 2019 Dec 18.

Abstract

Charcot-Marie-Tooth disease (CMT) is a hereditary sensory-motor neuropathy characterized by a strong clinical and genetic heterogeneity. Over the past few years, with the occurrence of whole-exome sequencing (WES) or whole-genome sequencing (WGS), the molecular diagnosis rate has been improved by allowing the screening of more than 80 genes at one time. In CMT, except the recurrent PMP22 duplication accounting for about 60% of pathogenic variations, pathogenic copy number variations (CNVs) are rarely reported and only a few studies screening specifically CNVs have been performed. The aim of the present study was to screen for CNVs in the most prevalent genes associated with CMT in a cohort of 200 patients negative for the PMP22 duplication. CNVs were screened using the Exome Depth software on next generation sequencing (NGS) data obtained by targeted capture and sequencing of a panel of 81 CMT associated genes. Deleterious CNVs were identified in four patients (2%), in four genes: GDAP1, LRSAM1, GAN, and FGD4. All CNVs were confirmed by high-resolution oligonucleotide array Comparative Genomic Hybridization (aCGH) and/or quantitative PCR. By identifying four new CNVs in four different genes, we demonstrate that, although they are rare mutational events in CMT, CNVs might contribute significantly to mutational spectrum of Charcot-Marie-Tooth disease and should be searched in routine NGS diagnosis. This strategy increases the molecular diagnosis rate of patients with neuropathy.

MeSH terms

  • Adolescent
  • Adult
  • Charcot-Marie-Tooth Disease / genetics*
  • Charcot-Marie-Tooth Disease / pathology
  • Child
  • Child, Preschool
  • Comparative Genomic Hybridization
  • Cytoskeletal Proteins / genetics*
  • DNA Copy Number Variations / genetics
  • Exome / genetics
  • Exome Sequencing
  • Female
  • Genetic Predisposition to Disease / genetics
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Male
  • Microfilament Proteins / genetics*
  • Middle Aged
  • Mutation / genetics
  • Nerve Tissue Proteins / genetics*
  • Phenotype
  • Ubiquitin-Protein Ligases / genetics*
  • Young Adult

Substances

  • Cytoskeletal Proteins
  • FGD4 protein, human
  • GAN protein, human
  • GDAP protein
  • Microfilament Proteins
  • Nerve Tissue Proteins
  • LRSAM1 protein, human
  • Ubiquitin-Protein Ligases