Abstracts

Rationale: Ring chromosome 20 syndrome (r20) is a rare genetic intractable epilepsy syndrome. Since 1972, when r20 was first reported, fewer than 200 cases have been reported worldwide and its long-term prognosis is rarely reported. We investigated the prognosis of seizure, as well as cognitive and social aspects retrospectively

Methods: Of the patients who visited our hospital, patients diagnosed with r20 based on clinical presentation and chromosome examination were included, and clinical information including treatment and psychosocial status was extracted from their medical records for analysis. Because the intensity of the symptoms, especially of nonconvulsive status epilepticus (NCSE), varies from subtle to prominent, we used the classification described below for seizure prognosis in this study, focusing on the perspective of disruption in daily life. Non-disabling seizure (NDS): either only seizures during sleep or seizures while awake but unnoticed by others and not disabling; Minimal disabling seizure (MDS): seizures that are noticed by others but are minimally disabling; Disabling seizure (DS); seizures that are neither NDS nor MDS. Clinical variables were compared between NDS + MDS (favorable seizure prognosis group) and DS (poor seizure prognosis group).

Results: Fourteen-seven patients were included (17 males and 30 females). The median age at epilepsy onset was 7 years (range 1-15) and the age at last follow-up (LF) was 20.5 years (9-70). Median ring chromosome 20 mosaicism rate (n=37) was 30% (3-97). Ten patients (21.3%) had NDS, 4 patients (8.5%) had MDS and 33 patients (70.2%) had DS. Of the patients with DS, 20 had daily (14 had NCSE), 12 had weekly, and 1 had yearly seizures. Median IQ (n=38) was 69; IQ >70 in 16 patients; IQ < 70 in 22; intellectual disability was noted in 5 of 9 patients with unknown IQ score; developmental delay prior to epilepsy onset was noted in 7; autism was noted in 8. Of the 30 patients over the age of 18 years at LF, 7 were employed, 5 had been employed previously but were unemployed at the time of the study, 3 were employed as disabled, 6 received employment support, 3 were college students, and 6 had no employment history. Three patients lived alone, two in institutions, and the others lived with their families. Two were married and one had given birth. One had obtained a driver's license but was not driving. The favorable seizure prognosis group had a significantly higher age at epilepsy onset, a lower rate of mosaics, a higher score of recent IQ, and a higher rate of lamotrigine use.

Conclusions: Thirty percent of the r20 patients improved with medication to the point where their seizures were barely interfering with their daily lives, even if not completely suppressed. On the other hand, given the seizure status, social constraints such as employment, marriage, and residence were significant, suggesting the need for comprehensive care.


Funding: No funding was received towards this work