SCN9A and primary erythermalgia: More importantly, rare variants that replace the conserved valine with alanine in the homologous positions of NaV1.7 (p.V1613A) [59] and NaV1.9 channels (p.V1184A) [42], both expressed in sensory neurons, have been causally linked with primary erythromelalgia and cold-aggravated peripheral pain episodes, respectively, suggesting that alteration p.V1287I likely alters functional properties of NaV1.8 and may be related to the patient’s symptoms.