Erythromelalgia Caused by the Missense Mutation p.Arg220Pro in an Alternatively Spliced Exon of SCN9A (NaV1.7)


Human Molecular Genetics 33, no. September 2023 (2023): 103–9


Jennifer R Deuis, Smitha Kumble, Angelo Keramidas, Lotten Ragnarsson, Cas Simons, Lynn Pais, Susan M White, and Irina Vetter



Erythromelalgia (EM), is a familial pain syndrome characterized by episodic ‘burning’ pain, warmth, and erythema. EM is caused by monoallelic variants in SCN9A, which encodes the voltage-gated sodium channel (NaV) NaV1.7. Over 25 different SCN9A mutations attributed to EM have been described to date, all identified in the SCN9A transcript utilizing exon 6N. Here, we report a novel SCN9A missense variant identified in seven related individuals with stereotypic episodes of bilateral lower limb pain presenting in childhood. The variant, XM_011511617.3:c.659G>C;p.(Arg220Pro), resides in the exon 6A of SCN9A, an exon previously shown to be selectively incorporated by developmentally regulated alternative splicing. The mutation is located in the voltage-sensing S4 segment of domain I, which is important for regulating channel activation. Functional analysis showed the p.Arg220Pro mutation altered voltage-dependent activation and delayed channel inactivation, consistent with a NaV1.7 gain-of-function molecular phenotype. These results demonstrate that alternatively spliced isoforms of SCN9A should be included in all genomic testing of EM.


Keywords: Q4 2023

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