Developmental and epileptic encephalopathies (DEEs) are a group of severe, early 
onset epilepsies characterized by refractory seizures, developmental delay or 
regression associated with ongoing epileptic activity, and generally poor 
prognosis. DEE is genetically and phenotypically heterogeneous, and there is a 
plethora of genetic testing options to investigate the rapidly growing list of 
epilepsy genes. However, more than 50% of patients with DEE remain without a 
genetic diagnosis despite state-of-the-art genetic testing. In this review, we 
discuss the major advances in epilepsy genomics that have surfaced in recent 
years. The goal of this review is to reach a larger audience and build a better 
understanding of pathogenesis and genetic testing options in DEE.