Developmental and Epileptic Encephalopathy 66, also known as dee66, is related to developmental and epileptic encephalopathy and hypotonia. An important gene associated with Developmental and Epileptic Encephalopathy 66 is PACS2 (Phosphofurin Acidic Cluster Sorting Protein 2), and among its related pathways/superpathways is Lissencephaly gene (LIS1) in neuronal migration and development. Affiliated tissues include brain, and related phenotypes are intellectual disability and seizure