The shared features of the four patients with FOXG1 mutations in our study were as follows: early global developmental delay and later severe mental retardation; hypotonia; failure to acquire speech or purposeful hand movements; deficient social interactions including poor eye contact, denoting a syndromic form of autism at an early age; combined stereotypic movements and dyskinesia with mixed features of athetosis, chorea, and dystonia; epilepsy with partial seizures accompanied by cyanosis; and hypoplasia of the corpus callosum along with underdevelopment of the frontal lobes. This evidence concerns the gene FOXG1 and Dyskinesia.