In a study of 110 patients with epileptic encephalopathy, genetic causes were identified in 28%. Inherited metabolic disorders were present in 7% and other genetic causes, including genetic syndromes, in 21%. Some 4.5% of patients had a treatable inherited metabolic disease. Diagnosis was obtained by epileptic encephalopathy genome sequencing panels for 45% of patients. The study was published online March 25 in Epilepsia.
http://www.ncbi.nlm.nih.gov/pubmed/25818041?dopt=Abstract