60 Investigating Setd2 Mutations in Neurodevelopment Using Cerebral Organoid Models

Somatic mutations in histones and histone modifiers define high-grade glioma subgroups in children and young adults. Mutations in SET Domain Containing 2 (SETD2), a histone methyltransferase responsible for catalyzing H3K36me3, are associated with both childhood glioma brain tumours and neurodevelopmental syndromes. SETD2 has been identified in 15% of pediatric high-grade gliomas (HGGs) localized to cerebral hemispheres, where reduced levels of H3K36me3 are exhibited, indicating a loss-of-function (LOF) mutation with poor prognosis. Similarly, SETD2 LOF mutation is observed in Luscan-Lumish Syndrome (SETD2+/-), a germline neurodevelopmental disorder characterized by macrocephaly, overgrowth, and autism. In striking contrast, Rabin-Pappas Syndrome (SETD2+/R1740W) results in microcephaly, undergrowth, and severe developmental delays. The mechanism behind the pathological mechanism of SETD2 mutations remains unknown in the context of human neurodevelopment. Here, CRISPR-Cas9 was used to introduce SETD2 mutations in human embryonic stem cells (hESCs), creating an isogenic model to study their epigenetic and transcriptional effects. The mutants were also modeled in 3D cerebral organoids to assess their impact on cell differentiation during early brain development in-vitro. Our preliminary results highlight distinct epigenetic and transcriptional dysregulation caused by SETD2 mutations, offering insights into their role in HGGs and neurodevelopment. These mutant models may guide future therapeutic development and advance knowledge of chromatin regulation in the human brain.