MODELLING THE <EM>SCN2A</EM> DISEASE SPECTRUM BY USING PATIENT INDUCED PLURIPOTENT STEM CELL-DERIVED CORTICAL TISSUE

SCN2A is one of the most significant single-gene contributors to neurodevelopmental disorders, from devastating developmental and epileptic encephalopathies (DEEs) to autism with or without seizures. To date, there are no effective treatments available to ameliorate both epilepsy and developmental deficits in these patients.
Advancing our knowledge of the pathomechanisms in the human biology context would be beneficial to progress toward the identification of new therapeutic targets and ultimately for the development of effective treatments.
In this study, we took advantage of iPSC technologies to investigate the pathomechanisms of distinctive variants identified in three patients whose clinical manifestations span the SCN2A disease spectrum. We performed a suite of molecular (QPCR and bulk RNA sequencing), cellular (immunocytochemistry) and functional experiments (patch clamping and Ca Imaging), to characterise our models and shed light on pathophysiology of SCN2A-related disorders.
Our transcriptomic analysis revealed a time-dependent profound dysregulation of corticogenesis – mainly patterning and cellular specification - for the R1882Q and R853Q variants, correlating with the SCN2A overexpression. For the S1758R variant, a distinctive driving mechanism was revealed by immunocytochemistry analysis pointing toward an impaired GABAergic commitment. To comprehensively model SCN2A disorders, we interrogated the functional properties of both 2D neurons and cortical organoids which revealed some electrophysiological alterations at both cellular and networking level.
In this study, we established in vitro models of SCN2A disease spectrum which unravelled emerging neurodevelopmental mechanisms in addition to recapitulating epileptic disease features and suggesting a non-canonical role of SCN2A in regulating early corticogenesis.