Epilepsy is noted in the 80-90% of patients with Angelman syndrome. Epileptic seizures debut at the age of 3 months to 20 years, but more often before 2 years, usually with febrile – provoked character.

Clinical case. Female K., 4 years old. Complaints: delay in psycho-speech development, restless sleep, cramps, tremor, and seizure. The first epileptic seizures appeared on good background at 1 year 2 months. As the attacks increased, the child began to experience delayed psychomotor development and muscle hypotension. Paroxysms were atonic character.

In neurological status: there is no pathology from the cranial nerves. In the motor sphere: muscle tone is hypotonic. Severe tremor of the trunk and extremities. Expressed motor delay: does not walk, stands with support, takes objects with hands. Active speech is absent, hardly understands the converted speech. The mood is fixed, a constant smile on his face, periodically laughs. Frequent stereotype movements in the hands.

On the video-EEG monitoring: slow-wave activity originating from the central-parietal divisions at a frequency of 3 Hz in all stages of Non-REM.

MRI of the brain - signs of moderate hypoxic - ischemic encephalopathy, delayed myelination.

Conclusion of the exome sequencing (WES): on chromosome-15 was detected a chromosomal microdeletion. It should be noted that the UBE3A gene is entered the deletion region (OMIM 105830 Angelman syndrome), heterozygous mutations of this gene leads to the clinical manifestations of AS.

Depends on type of seizures and according to EEG data, we can not attribute this case to classical encephalopathies of early childhood.