Characteristics of infantile convulsions and choreoathetosis syndrome caused by PRRT2 mutation

IMPORTANCE: Infantile convulsions and choreoathetosis (ICCA) is a rare neurological disorder. Many affected patients are either misdiagnosed or prescribed multiple antiepileptic drugs. OBJECTIVE: To explore therapeutic drug treatments and dosages for ICCA in children. METHODS: Detailed clinical features (e.g., past medical history and family history), genetic features, and treatment outcomes were collected from the records of six patients with ICCA. RESULTS: Mean age at paroxysmal kinesigenic dyskinesia (PKD) onset was 8 years 8 months (range, 3–12 years); the clinical presentation was characterized by daily short paroxysmal episodes of dystonia/dyskinesia. All patients had infantile convulsions at less than 1 year of age, and the mean onset age was 5.5 months (range, 4–7 months). Two patients had a family history of ICCA, PKD, or benign familial infantile epilepsy. Whole exome sequencing identified the c.649–650insC mutation in PRRT2 in six patients; three mutations were inherited and three were de novo. All patients were prescribed low‐dose carbamazepine and showed dramatic improvement with the complete disappearance of dyskinetic episodes after 3 days. They attended follow‐up for 5–17 months and were attack‐free until the final follow‐up. INTERPRETATION: PRRT2 mutations are the primary cause of ICCA. Low‐dose carbamazepine monotherapy is effective and well‐tolerated in children.