Objective: We retrospectively investigated a cohort of patients with ring chromosome 20 syndrome (r20), aiming to provide information on the prognosis of r20 regarding seizures, cognitive function, comorbidities, and social living.

Methods: Patients diagnosed with r20 in our hospital were identified, and clinical data were extracted from medical records. We used the following seizure outcome classification: favorable seizure outcome, a condition in which seizures do not interfere with daily life, including no seizures, subclinical discharges, sleep seizures or mild focal aware seizures; poor seizure outcome, a condition in which seizures interfere with daily life. Clinical variables were compared between favorable and poor seizure outcome groups.

Results: Forty-seven patients (64% female) were studied. Mean age ± standard deviation (SD) at epilepsy onset was 7.5 ± 3.7 (range 1-15) years. Mosaicism rate was 33 ± 24% (range 1%-97%). Fourteen patients (30%) were classified in the favorable seizure outcome group and 33 (70%) in the poor seizure outcome group. Multivariable analysis identified lower mosaicism rate and higher rate of lamotrigine use as independent factors associated with a favorable seizure outcome. The most effective drug was lamotrigine (69%), followed by valproate (43%) and other sodium channel blockers. Intellectual disability was present in 27 patients (57%), autism spectrum disorder in 8 (17%), and psychiatric symptoms in 10 (21%). Of 30 adult patients, 7 (23%) were employed, 5 (17%) were employed previously but unemployed at the last follow-up, 3 (10%) were employed as disabled, 6 (20%) received employment support, 3 (10%) were college students, and 6 (20%) had no employment history. Twenty-five patients (83%) lived with their families. Two patients (7%) were married.

Conclusions: In 30% of r20 patients, drug treatment improved seizures to a degree minimally disruptive to daily life. Lamotrigine use was associated with favorable seizure outcome. Social constraints in employment, residence, and marriage were significant, indicating the need for comprehensive epilepsy care.