Cortical organoids model early brain development disrupted by 16p11.2 CNV in autism

Reciprocal deletion and duplication of 16p11.2 is the most common copy number variation (CNV) associated with Autism Spectrum Disorder (ASD) and other developmental disorders, and has significant effect on brain size. We used cortical organoids derived from ASD cases to investigate neurodevelopmental pathways dysregulated by dosage changes of 16p11.2 CNV. We show that organoids recapitulate patients’ macrocephaly and microcephaly phenotypes. Deletions and duplications have “mirror” effects on cell proliferation, maturation and synapse number, consistent with “mirror” effects on brain development in humans. Neuronal migration was decreased in both, deletion and duplication organoids. Transcriptomic and proteomic profiling revealed synaptic defects and neuronal migration as key drivers of 16p11.2 functional effect. We implicate upregulation of small GTPase RhoA involved in regulation of cytoskeletal dynamics, neuron migration and neurite outgrowth as one of the pathways impacted by the 16p11.2 CNV in ASD. Treatment with the RhoA inhibitor Rhosin rescued neuron migration, but not synaptic defects. This study identifies pathways dysregulated by the 16p11.2 CNV during early neocortical development using cortical organoid models. Grant ID: Simons Foundation, #345469 Grant Title: Translational dysregulation of the RhoA pathway in autism Affiliation: University of California San Diego Name: Lilia M. Iakoucheva; Alysson R. Muotri Bulk RNA-seq of 108 samples of patient-derived iPSCs, 1 month old and 3 months old cortical organoids with 16p11.2 deletions, duplications and controls was performed