Conversely, BE has been associated with mutations in the X-linked gene SYN1 that encodes 1 of the 3 Synapsins (SYN1–SYN3), a family of phosphoproteins involved in synaptic development, function, and plasticity.13,14 In addition to seizures triggered by water, SYN1 mutations are responsible for a wide range of neurodevelopmental disorders, including cognitive impairment, autism spectrum disorders (ASD), and unprovoked seizures.15,16 To date, SYN1 mutations have been described in 9 patients with BE17, -, 19 and 1 patient with HWE.20 Here, SYN1 is linked to Cognitive impairment.