Neuropathic pain in two-generation twins carrying the sodium channel Nav1.7 functional variant R1150W.
Pain
; 155(10): 2199-203, 2014 Oct.
Article
in En
| MEDLINE
| ID: mdl-25116815
ABSTRACT
We present clinical, neuropathological, and molecular genetic findings of a family with a new pain phenotype of the sodium channel gene SCN9A polymorphism R1150W. A 46-year-old woman presented with a 5-year history of episodic temperature- and exercise-dependent burning pain of the feet and lower legs associated with numbness of the distal upper and lower limbs. Her monozygotic twin sister and their mother and her twin presented similar symptoms. Clinical evaluation was normal except for a mild distal sensory deficit in fingers and feet. Electrophysiological testing was unremarkable, as were serum and cerebrospinal fluid laboratory findings. Skin biopsies of the distal lower limbs revealed an epidermal nerve fiber density at the lower limit of normal. Myelinated dermal nerve fibers showed elongated nodes of Ranvier, but normal distribution of nodal and paranodal proteins. Genetic testing for ion channel-associated pain disorders revealed an amino acid R1150W substitution of the Nav1.7 sodium channel. The combination of a Nav1.7 polymorphism with dysmyelinating features in small-caliber peripheral nerves has not been described before and may suggest an explanation for the clinical syndrome in our patients. Treatment with the sodium channel blocker lamotrigine provided some relief, consistent with a role of sodium channel dysfunction in the pain syndrome of this family.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
NAV1.7 Voltage-Gated Sodium Channel
/
Neuralgia
Limits:
Female
/
Humans
/
Middle aged
Language:
En
Journal:
Pain
Year:
2014
Document type:
Article
Affiliation country:
Alemania