Relationships between PRRT2 variants and clinical outcomes in infants with suspected self-limited infantile epilepsy.

OBJECTIVE: To compare the seizure and developmental outcomes according to the presence/absence of pathogenic PRRT2 variants in patients with clinically suspected self-limiting infantile epilepsy (SeLIE), to thereby clarify the prognostic value of PRRT2 testing. METHODS: Forty-two patients with clinically suspected SeLIE were assessed. Clinical information, including patient and seizure characteristics, final diagnosis, and developmental outcomes, were retrospectively obtained. Genetic testing for PRRT2 was conducted using Sanger sequencing, and patients were classified as PRRT2-positive or PRRT2-negative based on the presence/absence of pathogenic PRRT2 variants. The clinical characteristics, seizures, and developmental outcomes were further compared between the groups. RESULTS: Pathogenic PRRT2 variants were identified in 14 of 42 patients. PRRT2-positive patients more commonly had a family history of SeLIE/paroxysmal kinesigenic dyskinesia (71.4%vs. 17.9%) and had a younger median age at first seizure (6 vs. 7 months) than PRRT2-negative patients. All patients in the PRRT2-positive group were finally diagnosed with SeLIE, whereas 9 of the 28 PRRT2-negative patients (32.1%) were classified as having other epilepsies. Developmental delay was observed only in the PRRT2-negative group (7/28, 25.0%), although the difference between the groups was not statistically significant (P = 0.075). Patients with developmental delay were less likely to achieve seizure freedom after anti-seizure medication treatment than those with normal development (50.0%vs. 93.3%, P = 0.024). CONCLUSION: In infants with clinically suspected SeLIE, PRRT2 testing is useful for predicting seizures and developmental outcomes.