Ring (20) chromosome epileptic syndrome

Abstract

Ring (20) chromosome epilepsy syndrome is characterized by highly refractory epilepsy that is often associated with non-pathognomonic, electroencephalographic (EEG) changes. Seizures typically begin during the stage of childhood around the age of 6 years. Nonconvulsive status epilepticus (NCSE) is the most common seizure types and is distinguished by a long-lasting, confusional state that is often associated with EEG patterns in the form of prolonged, high-voltage slow waves with occasional spike/sharp components. Patients with this syndrome suffer from intractable seizures with cognitive decline and frequent epileptic episodes. Accompanying features of this rare disorder, such as superficial minor dysmorphic abnormalities if any, mental retardation and behavioral changes are quite variable. Because of the variability in clinical presentation, in particular the lack of clear dysmorphic features, the clinical diagnosis of this disorder can be delayed before being diagnosed genetically. Most patients with this syndrome have chromosomal changes in the form of a mosaic. High levels of mosaicism correlate well with a lower age of onset and severe cognitive impairment. Here, we emphasize the importance of early G-banding chromosomal analysis when patients present with unexplainable severe seizures and repetitive NCSE, even in the absence of any dysmorphic features suggestive of a chromosomal disorder.