Any early infantile epileptic encephalopathy in which the cause of the disease is a mutation in the AP3B2 gene. The disease is Monarch Disease Ontology term MONDO_0015000 (developmental and epileptic encephalopathy, 48). Also known as: AP3B2 early infantile epileptic encephalopathy, DEE48, EIEE48, developmental and epileptic encephalopathy 48, early infantile epileptic encephalopathy caused by mutation in AP3B2, epileptic encephalopathy, early infantile, 48, epileptic encephalopathy, early infantile, 48; EIEE48, epileptic encephalopathy, early infantile, type 48.