Ring chromosome 20: a further contribution to the delineation of epileptic phenotype

Milan Borković; Goran Čuturilo; Natasa Cerovac

doi:10.2298/VSP200601096B

Milan Borković Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia
Goran Čuturilo University of Belgrade, Faculty of Medicine, Belgrade, Serbia
Natasa Cerovac Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia; University of Belgrade, Faculty of Medicine, Belgrade, Serbia

DOI: https://doi.org/10.2298/VSP200601096B

Keywords: chromosome aberrations;, clinical medicine;, cognitive dysfunction;, drug resistant epilepsy;, ring chromosome 20 syndrome;, drug therapy

Abstract

Introduction. Ring chromosome 20 [r(20)] syndrome is a rare genetic abnormality where two arms of the 20th chromosome fuse forming a ring chromosome, resulting in intractable epilepsy and wide range of behavioral problems and cognitive deficits. Case report. We presented four patients with r (20) syndrome diagnosed between the years 2000–2018. In all patients we analyzed clinical epilepsy features (seizure semiology, seizure frequency/drug response, the presence of nonconvulsive status epilepticus), cognitive status and the phenotype characteristics. The average age of epilepsy onset was 6 years. All four patients had nocturnal epileptic events and normal brain magnetic resonance (MR) imaging. Dysmorphism was present in two children, behavioral problems also in two children and intellectual disabilities were observed in three children. R(20) syndrome mosaicism ranged between 17% and 83% of blood lymphocytes. Conclusion. Despite the small size of our group, we think that our findings have clinical relevance. Refractory childhood onset epilepsy and especially the occurrence of nocturnal epileptic events should help physicians to recognize this chromosomopathy. Routine karyotyping can be employed to identify the patients easily.

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