TARGETING <EM >KCNA2</EM> GAIN-OF-FUNCTION DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY: FROM GENETIC TO PHARMACOLOGICAL TREATMENT STRATEGIES

KCNA2 encephalopathy is a rare, early-onset neurological disorder characterized by severe epilepsy and developmental delay. De novo gain-of-function (GOF) variants in KCNA2, which encodes the voltage-gated potassium channel subunit K_V1.2, increase channel activity and cause premature opening. However, the mechanisms by which KCNA2 GOF variants drive epileptogenesis remain poorly understood. To investigate the pathology, we generated a Kcna2 knock-in mouse model carrying the Kcna2 GOF variant p.Arg297Gln. The mice exhibited a severe seizure phenotype and died prematurely, which we analyzed using video/EEG-recordings. We also observed a hypoactivity in the mice during PhenoMaster experiments. Single-cell recordings in acute brain slices demonstrated a hypoactivity in L2/3 pyramidal neurons in the somatosensory cortex. Treatment with the potassium channel blocker 4-aminopyridine significantly prolonged the lifespan of heterozygous mice. Nevertheless, 4-AP does not selectively bind to K_V1.2. To address this, we aim to develop antisense oligonucleotides (ASOs) that selectively reduce the expression of the K_V1.2 channel subunit. We generated and optimized ASOs targeting Kcna2, which showed selective and dose-dependent downregulation of Kcna2 in murine primary cortical neurons. Further, a similar effect of the ASOs was observed in neural networks derived from human induced pluripotent stem cells. The next step will involve assessing the tolerability and efficacy of the ASO treatment on the epileptic phenotype in vivo. In summary, we have generated a Kcna2 GOF knock-in mouse model that mimics the phenotype observed in patients. This will enhance our understanding of the Kcna2-related encephalopathy and ultimately facilitate the development of targeted treatments using Kcna2-selective ASOs.