No mutations in the voltage‐gated NaV1.7 sodium channel α1 subunit gene SCN9A in familial complex regional pain syndrome

Background: Mutations in the voltage‐gated Na_V1.7 Na⁺ channel α1 gene SCN9A have been linked to pain disorders, such as inherited primary erythromelalgia and paroxysmal extreme pain disorder. Both show clinical overlap with complex regional pain syndrome (CRPS), a condition that is characterized by pain in association with combinations of vasomotor, sudomotor, sensory, and motor disturbances. Therefore, we here investigated the involvement of the SCN9A gene in familial CRPS. Methods: We performed a mutation analysis of the SCN9A gene in four index cases of families with CRPS. All 26 coding exons and adjacent sequences of the SCN9A gene were analyzed for mutations using direct sequencing analysis. Results: No causal gene mutations were identified in the SCN9A gene in any of the patients. Conclusions: Despite the fact that the SCN9A gene is an excellent candidate, we did not find evidence that it plays a major role in familial CRPS.