FGF12 (FHF1) (fibroblast growth factor 12): Two siblings affected by neonatal-onset EE with tonic seizures and a characteristic neonatal EEG pattern (interictal: severe background slowing and multifocal discharges, ictal: low voltage fast activity, followed by prolonged background suppression) with normal neurologic status prior to seizure onset, subsequently developed a complex phenotype with hypotonia, microcephaly, feeding difficulties, cerebral visual impairment with pale optic nerve disc, and limb ataxia. Here, FGF12 is linked to microcephaly.