Genetic features and pharmacological rescue of novel Kv7.2 variants in patients with epilepsy

Increasing evidence indicates a robust correlation between epilepsy and variants of the Kv7.2 (KCNQ2) channel, which is critically involved in directing M-currents and regulating neuronal excitability within the nervous system. With the advancement of next-generation sequencing, the identification of KCNQ2 variants has surged. Nonetheless, their functional impacts are still being determined, introducing uncertainty into the diagnostic process for affected families and potentially hindering their ability to participate in targeted precision medicine trials. This study aims to elucidate the pathogenicity of these novel variants and explore potential therapeutic interventions.

Whole-cell patch-clamp recordings, western blotting, and immunofluorescent staining were performed to elucidate the functional consequences of the identified variants. Moreover, coimmunoprecipitation techniques were conducted to explore protein interactions, thus facilitating a deeper understanding of the underlying pathogenetic mechanisms contributing to the disease. Ultimately, the effects of pharmacological interventions were evaluated in vitro using the patch-clamp technique.

Herein, we identified 12 novel KCNQ2 variants, further expanding the mutational spectrum of KCNQ2. Our investigation revealed that one gain-of-function variant (p.L102V (c.304C>G)) and three loss-of-function variants (p.H328Q (c.984C>G), p.A336V (c.1007C>T) and p.D563Efs*22 (c.1688_1689insACTT)) had different impacts on the binding of calmodulin and phosphati-dylinositol-4,5-bisphosphate, potentially altering their localisation and protein stability. Furthermore, the application of ML213, unlike Retigabine and ICA-069673, led to a significant increase in the current of p.H328Q.

This study expanded the mutational spectrum of KCNQ2 and analysed the genetic and functional consequences, as well as the pharmacological rescue, of four de novo KCNQ2 variants. These findings offer valuable insights into the precise medicine of KCNQ2-related epilepsy.