SCN10A Mutation in a Patient with Erythromelalgia Enhances C-Fiber Activity Dependent Slowing

PLoS One. 2016 Sep 6;11(9):e0161789. doi: 10.1371/journal.pone.0161789. eCollection 2016.

Abstract

Gain-of-function mutations in the tetrodotoxin (TTX) sensitive voltage-gated sodium channel (Nav) Nav1.7 have been identified as a key mechanism underlying chronic pain in inherited erythromelalgia. Mutations in TTX resistant channels, such as Nav1.8 or Nav1.9, were recently connected with inherited chronic pain syndromes. Here, we investigated the effects of the p.M650K mutation in Nav1.8 in a 53 year old patient with erythromelalgia by microneurography and patch-clamp techniques. Recordings of the patient's peripheral nerve fibers showed increased activity dependent slowing (ADS) in CMi and less spontaneous firing compared to a control group of erythromelalgia patients without Nav mutations. To evaluate the impact of the p.M650K mutation on neuronal firing and channel gating, we performed current and voltage-clamp recordings on transfected sensory neurons (DRGs) and neuroblastoma cells. The p.M650K mutation shifted steady-state fast inactivation of Nav1.8 to more hyperpolarized potentials and did not significantly alter any other tested gating behaviors. The AP half-width was significantly broader and the stimulated action potential firing rate was reduced for M650K transfected DRGs compared to WT. We discuss the potential link between enhanced steady state fast inactivation, broader action potential width and the potential physiological consequences.

Publication types

  • Case Reports

MeSH terms

  • Action Potentials / genetics
  • Electric Stimulation
  • Erythromelalgia / genetics*
  • Erythromelalgia / physiopathology
  • Ganglia, Spinal / metabolism*
  • Ganglia, Spinal / pathology
  • Humans
  • Male
  • Middle Aged
  • Mutation
  • NAV1.8 Voltage-Gated Sodium Channel / genetics*
  • Nerve Fibers, Unmyelinated
  • Pain / genetics*
  • Pain / physiopathology
  • Patch-Clamp Techniques
  • Sensory Receptor Cells / metabolism
  • Sensory Receptor Cells / pathology
  • Tetrodotoxin / genetics

Substances

  • NAV1.8 Voltage-Gated Sodium Channel
  • SCN10A protein, human
  • Tetrodotoxin

Grants and funding

The project was supported by AstraZeneca (Södertälje, Sweden). Research was supported by the German Research Council (DFG, NA 970/1-1 to BN, LA2740/2 1 to AL; SFB 1158 project A1 to MS), ELAN (Erlanger Leistungsbezogene Anschubfinanzierung und Nachwuchsförderung) of the FAU Erlangen-Nürnberg (11.05.30.1 to AL) and the German Israeli Foundation (GIF, 1091-27.1/2010 to AL). Dagrun Sagafos and Lars Kristian Lunden are supported by the Research line of the Medical Faculty, University of Oslo. Employees of one of the funders (AstraZeneca, listed as authors) had a role in study design, data interpretation, decision to publish and preparation of the manuscript. Other funders had no such direct roles in the study.