Abstracts

Rationale: PRRT2 located in chromosome 16p11.2 is known to be a causative gene of paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), and infantile convulsion with choreoathetosis (ICCA). This study is to describe clinical manifestations and PRRT2 mutation detected in Korean pediatric patients with PKD or BFIE. Methods: Thirty-nine participants (male 32, female 7) were enrolled in this study comprised 25 patients clinically diagnosed with PKD, 13 patients with BFIE, and one patient having both. We investigated PRRT2 mutation by direct sequencing of genomic DNA and reviewed medical records of all participants retrospectively. Results: Twenty-six patients with PKD included 5 familial cases and male predominated. Dyskinesia arose in the mean age of 12.6±3.0 (range 7–18) years and involved limb (n=18) and trunk (n=8). All patients except one were treated with medications and were controlled well. Patients with BFIE had first seizure at the mean age of 4.9±1.8 months and were free of seizures before age of 2 years except one (9-month-old) being under the treatment. Their brain magnetic resonance imaging and interictal electroencephalogram were normal and prognosis was good showing normal developmental milestones. The heterozygous PRRT2 mutation was found in 23 (59.0%) of 39 probands. The most common mutation, c.649dupC (p.R217Pfs*8), was found in 9 patients with PKD, 11 with BFIE, and one having both. Two other patients with BFIE, who were siblings, had a different mutation, c.971delG (p.G324fs), which has not been reported. Conclusions: Manifestation of PRRT2 mutation can express various phenotypes on patients’ age. Most cases of PRRT2 mutation have favorable response to treatments and self-limited course irrespective to clinical presentation. Further study is needed to reveal other genetic or environmental factors relating to the mechanism causing different disorders from one genetic mutation. Funding: The National Research Foundation of Korea (NRF-2017R1D1A1B03034685)