Monarch Disease Ontology entry MONDO_0013389 (developmental and epileptic encephalopathy, 12) is an extremely rare nervous system disorder. Infants with EIEE12 develop very frequent epileptic seizures. Seizures present within the first days to months of life. Seizures may trigger eye rolling, eyelid fluttering, lip smacking, drooling, bluish coloring around the mouth, limpness, or muscle stiffening (particularly those in his or her back, legs, and arms). The seizures associated with this disease are difficult to treat and the syndrome is severely progressive. EIEE12 occurs when a child inherits two mutations in the PLCB1 gene (one from each parent). EIEE12 is inherited in an autosomal recessive fashion. Also known as: DEE12, EIEE12, PLCB1 early infantile epileptic encephalopathy, developmental and epileptic encephalopathy 12, early infantile epileptic encephalopathy 12, early infantile epileptic encephalopathy caused by mutation in PLCB1, epileptic encephalopathy, early infantile, 12, epileptic encephalopathy, early infantile, type 12.