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Developmental and epileptic encephalopathies (DEE) are a group of disorders associated with intractable seizures, brain development, and functional abnormalities, and in some cases, premature death. Pathogenic human germline biallelic mutations in tumor suppressor WW domain‐containing oxidoreductase (WWOX) are associated with a relatively mild autosomal recessive spinocerebellar ataxia‐12 (SCAR12) and a more severe early infantile WWOX‐related epileptic encephalopathy (WOREE). In this study, we generated an in vitro model for DEEs, using the devastating WOREE syndrome as a prototype, by establishing brain organoids from CRISPR‐engineered human ES cells and from patient‐derived iPSCs. Using these models, we discovered dramatic cellular and molecular CNS abnormalities, including neural population changes, cortical differentiation malfunctions, and Wnt pathway and DNA damage response impairment. Furthermore, we provide a proof of concept that ectopic WWOX expression could potentially rescue these phenotypes. Our findings underscore the utility of modeling childhood epileptic encephalopathies using brain organoids and their use as a unique platform to test possible therapeutic intervention strategies., Mutations in the human WWOX gene cause devastating developmental and neurological diseases in young children called WOREE syndrome and SCAR12 syndrome. Using both gene editing and reprogramming technologies these maladies can now be modeled in human brain organoids, allowing for molecular and electrophysiological study of the pathology, together with testing possible therapeutic interventions.

WW domain‐containing oxidoreductase (WWOX) is an emerging neural gene‐regulating homeostasis of the central nervous system. Germline biallelic mutations in WWOX cause WWOX‐related epileptic encephalopathy (WOREE) syndrome and spinocerebellar ataxia and autosomal recessive 12 (SCAR12), two devastating neurodevelopmental disorders with highly heterogenous clinical outcomes, the most common being severe epileptic encephalopathy and profound global developmental delay. We recently demonstrated that neuronal ablation of murine Wwox recapitulates phenotypes of Wwox‐null mice leading to intractable epilepsy, hypomyelination, and postnatal lethality. Here, we designed and produced an adeno‐associated viral vector (AAV9) harboring murine Wwox or human WWOX cDNA and driven by the human neuronal Synapsin I promoter (AAV‐SynI‐WWOX). Testing the efficacy of AAV‐SynI‐WWOX delivery in Wwox‐null mice demonstrated that specific neuronal restoration of WWOX expression rescued brain hyperexcitability and seizures, hypoglycemia, myelination deficits, and the premature lethality and behavioral deficits of Wwox‐null mice. These findings provide a proof‐of‐concept for WWOX gene therapy as a promising approach to curing children with WOREE and SCAR12., AAV‐mediated neuronal WWOX restoration reverses abnormal defects of Wwox null mice, providing a proof‐of‐concept for WWOX gene therapy as a promising approach for treating children with WOREE syndrome.