Researchers have uncovered a molecular mechanism linking alterations in the neuronal protein CPEB4 to idiopathic autism, which accounts for 80% of autism cases without a clear genetic cause. The study reveals that the absence of a specific microexon in CPEB4 disrupts the dynamics of molecular condensates in neurons, affecting the regulation of genes crucial for brain development. This disruption can lead to reduced protein production, impairing neuronal growth and function.