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