Investigators at the Institute for Research in Biomedicine (IRB Barcelona) have unraveled how and why the absence of a neuronal microexon in cytoplasmic polyadenylation element-binding 4 (CPEB4) gives rise to autism. In 2018, investigators from IRB, co-led by Raúl Méndez, identified the overt correlation between defects in CPEB4 and the onset of autism. However, the previous work did not provide the molecular mechanism explaining the correlation.