Gain-of-function Nav1.8 mutations in painful neuropathy

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Painful peripheral neuropathy, particularly small-fiber neuropathy, frequently lacks a clear etiological basis.
• Gain-of-function variants in the sodium channel Na(v)1.7 have been implicated in approximately 30% of idiopathic cases.

Observation:

• This study investigated mutations in the Na(v)1.8 sodium channel, which is selectively expressed in dorsal root ganglion (DRG) neurons and peripheral nerve axons.
• Seven distinct Na(v)1.8 mutations were identified in 9 out of 104 patients presenting with painful, predominantly small-fiber neuropathy.

Findings:

• Three of the identified Na(v)1.8 mutations were predicted as potentially pathogenic using computational algorithms.
• Functional analysis via voltage and current clamp revealed that two of these mutations enhance channel depolarization response, leading to DRG neuron hyperexcitability.

Implications:

• These findings indicate that Na(v)1.8 channel mutations are a contributing factor to the development of painful peripheral neuropathy.
• Targeting Na(v)1.8 may offer a novel therapeutic strategy for specific neuropathic pain conditions.