Researchers have identified a link between brain overgrowth and the severity of social and communication symptoms in children with autism spectrum disorder (ASD). By analyzing MRI scans and conducting experiments with brain organoids, the study found that children with the most severe ASD symptoms had significantly larger brains. This enlargement is associated with altered activity of the enzyme Ndel1, which plays a crucial role in neuron development. The findings open new avenues for understanding ASD and its varying symptom severity.