Targeted gene therapy alleviates epilepsy and hyperexcitability in models of SCN2A deficiency

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Abstract

Pathogenic SCN2A loss-of-function (LoF) variants can cause severe, refractory epilepsy with limited treatment options. Existing Scn2a-LoF mouse models exhibit few spontaneous seizures, limiting the dynamic range needed to assess therapeutic efficacy. We therefore generated gene-trap Scn2a-deficient mice on the seizure-prone DBA/2J background. These mice experienced hundreds of spontaneous absence seizures per day, characterized by concurrent behavioral arrest and EEG spike–wave discharges (SWDs). Partial restoration of Scn2a expression reduced seizure burden. Electrophysiological analysis revealed impaired action potential waveforms yet increased repetitive firing, alongside coordinated downregulation of voltage-gated potassium channel genes, potentially contributing to hyperexcitability. Given the broad potassium channel downregulation and prior efficacy of KCNA1 gene therapy in refractory seizure models, we selected KV1.1 as a potential therapeutic target and used a drug-controllable adeno-associated virus (AAV) to express human KCNA1. We found that this intervention normalized elevated neuronal firing and reduced spontaneous seizure burden in Scn2a-deficient mice. Extending these findings to a human cell-based platform, AAV-mediated KCNA1 expression also reduced neuronal firing in human cortical organoids carrying a SCN2A-truncating variant identified in patients. Together, these findings provide proof of principle for drug-controllable KCNA1 gene therapy as a promising treatment avenue for epilepsy related to SCN2A LoF variants.

Authors

Zaiyang Zhang, Jingliang Zhang, Xiaoling Chen, Brody A. Deming, Shivam Kant, Purba Mandal, Harish Kothandaraman, Phillip J. SanMiguel, Manasi S. Halurkar, Akila D. Abeyaratna, Morgan J. Robinson, Iuliia Vitko, Ronald P. Gaykema, Chongli Yuan, Nadia A. Lanman, Matthew T. Tegtmeyer, Dan Wang, Guangping Gao, Riyi Shi, Edward Perez-Reyes, Yang Yang