Early Myoclonic Encephalopathy in 9q33‐q34 Deletion Encompassing STXBP1 and SPTAN1

Summary Deletions in the 9q33‐q34 region have been reported in patients with early onset epileptic encephalopathy, but a consistent phenotype has yet to emerge. We report on the diagnosis of a de novo 9q33‐q34.12 microdeletion of 4 Mb in a 15‐month‐old girl presenting with severe psychomotor delay, facial dysmorphisms, thin corpus callosum and early myoclonic encephalopathy. This deletion encompasses 101 RefSeq genes, including the four autosomal dominant genes STXBP1 , SPTAN1 , ENG and TOR1A . We discuss genetic, clinical and epileptic features comparing our patient with those previously reported in the literature.