Variable epilepsy phenotypes associated with heterozygous mutation in the SCN9A gene: report of two cases
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Up to now, SCN9A mutations encoding Nav1.7 have been limited to inherited pain syndromes. A few of pathogenic SCN9A mutations with or without SCN1A mutations have been identified in epileptic patients. Here, we report two heterozygous SCN9A mutations with no SCN1A mutations, which are associated with variable epilepsy phenotypes and explored the possibility of SCN9A contributing to a multifactorial etiology for epilepsy. Our findings suggest that the two SCN9A mutations (c.980G>A chr2:167149868 p.G327E; c.5702_5706del chr2:167055410 p.I1901fs) should be regarded as pathogenic mutations. Two heterozygous mutations of SCN9A are associated with a wide clinical spectrum of seizure phenotypes including simple febrile seizures, afebrile seizures, generalized tonic-clonic seizure, myoclonic or tonic seizures, and focal clonic seizures. Patients with deletion mutations tend to be associated with more severe seizure type than missense mutations.
KeywordsSCN9A Heterozygous mutation Epilepsy Febrile seizures
We would like to thank the patient’s parents for providing written informed consent for the publication of the manuscript and any accompanying images.
This project was funded by grants from National Natural Science Foundation of China (81201511, 81671287) and Zhejiang Provincial Natural Science Foundation of China (LY15H090006).
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Conflict of interest
The authors declare that there are no conflicts of interest.
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