J Korean Child Neurol Soc.  2017 Dec;25(4):221-226. 10.26815/jkcns.2017.25.4.221.

Clinical Manifestation and PRRT2 Analysis of Korean Patients with Paroxysmal Kinesigenic Dyskinesia

• Kang SM
• Lee JH
• Cho KL
• Lee HJ
• Kim JE
• Seo EJ

• KMID: 2403724
• DOI: http://doi.org/10.26815/jkcns.2017.25.4.221

Abstract

PURPOSE
Paroxysmal kinesigenic dyskinesia (PKD) is a rare paroxysmal movement disorder characterized by recurrent and brief dyskinesia attacks triggered by sudden voluntary movement. The diagnosis of PKD is based on clinical findings, and mutations in the proline-rich transmembrane protein 2 (PRRT2) gene have been identified as the cause of PKD. Two Korean cohorts have been reported on PRRT2 mutation analysis in PKD patients. The purpose of this study was to determine the mutation spectrum of the PRRT2 gene and to examine the clinical characteristics associated with PRRT2 mutations.
METHODS
We studied 23 members of four families with familial PKD and two families with sporadic PKD which included 9 patients and 2 patients, respectively. Mutation analysis of the PRRT2 gene was performed using Sanger sequencing. Clinical features of PKD were compared between patients with a PRRT2 mutation and those with no detectable PRRT2 mutation.
RESULTS
PRRT2 mutations were detected in three of four PKD families (75%), and in none of the two sporadic cases (0%). All detected PRRT2 mutations were c.649dupC (p.Arg217Profs*8). Subjects with detected PRRT2 mutations had earlier age at onset and longer duration of attacks.
CONCLUSION
As previously reported in Korean PKD patients, our results confirmed that PRRT2 is a major causative gene for familial PKD, and the c.649dupC is the most frequent mutation. PRRT2 mutation analysis is required for the molecular diagnosis of familial PKD and for evaluating the clinical manifestations of PKD.

Keyword

Paroxysmal kinesigenic dyskinesia; PRRT2; Dystonia

MeSH Terms

Age of Onset
Cohort Studies
Diagnosis
Dyskinesias*
Dystonia
Humans
Movement Disorders