A homozygous loss-of-function (LoF) mutation, c.3709DelG, in contactin-associated-protein-like 2 (CNTNAP2) causes a rare and severe neurodevelopmental syndrome characterized by ASD, intellectual disability, early-onset epilepsy and an increase in head circumference – collectively termed Cortical Dysplasia Focal Epilepsy (CDFE) syndrome10. Here, CNTNAP2 is linked to epilepsy.