Patients with congenital Rett syndrome due to pathogenic variants in FOXG1 presented with typical clinical features such as progressive microcephaly, DD, corpus callosum anomalies, intellectual disability, epilepsy and strabismus but also rare findings including nystagmus (case S8 and S106) and previously unreported hypoplastic cranial nerves I and II (S8) [36]. This evidence concerns the gene FOXG1 and pathologic nystagmus.