Ten de novo CYFIP2 variants (6 intronic, 1 synonymous, and 3 missense) have been reported in patients with autism and developmental disorders.[8,9] Moreover, novel CYFIP2 variants have recently been identified in 5 patients with severe early-onset epileptic encephalopathies by 2 different research groups[4,5] and these pathogenic mutations have been functionally verified.[4] These CYFIP2 mutations were designated EIEE 65 (OMIM database). This evidence concerns the gene CYFIP2 and Epileptic encephalopathy.