Introduction: STXBP1 mutations are associated with early infancy epileptic encephalopathy and a characteristic phenotype has been described. We present two new patients with STXBP1 epileptic encephalopathy with different clinical phenotypes.

Case Description:

Patient 1

A 12 years-old male presented at day 3 of life with focal seizures and spasms, evolving to a West syndrome treated with vigabatrin. After a period of 6 years without seizures he started to have refractory epilepsy. The patient evolved with severe intellectual disability and motor delay. Currently he has an ataxic gait, no speech and he presents several stereotypies:  hands and head stereotypies, bruxism and hyperventilation alternating with apneic spells. He had a de novo STXBP1 mutation.

Patient 2

A 7 years-old female began focal seizures with automatisms on the first days of life, without burst suppression. At 1 month she presented epileptic spasms with interictal EEG showing anterolateral paroxysmal activity. She stayed seizures-free during 5 years on monotherapy. The patient acquired independent gait at 3 years-old and presently she combines two words. The microarray showed a deletion on long arm of chromosome 9 involving STXBP1 gene.

Discussion: The first patient illustrates the broad phenotypic spectrum of STXBP1 mutations and the need to consider this diagnosis in patients with a Rett like phenotype. The second patient has a milder phenotype than those previously described. She didn’t have Ohtahara or West syndromes and evolved to an easily controlled epilepsy and moderate intellectual disability. These case reports introduce diversity on STXBP1 mutations epileptic encephalopathy phenotype.