PRRT2 mutations in a cohort of Chinese families with paroxysmal kinesigenic dyskinesia and genotype–phenotype correlation reanalysis in literatures

<b>Purpose</b><b>of the study</b>: Though rare, children are susceptible to paroxysmal dyskinesias such as paroxysmal kinesigenic dyskinesia, and infantile convulsions and choreoathetosis. Recent studies showed that the cause of paroxysmal kinesigenic dyskinesia or infantile convulsions and choreoathetosis could be proline-rich transmembrane protein 2 (<i>PRRT2</i>) gene mutations. <b>Material and methods:</b> This study analysed <i>PRRT2</i> gene mutations in 51 families with paroxysmal kinesigenic dyskinesia or infantile convulsions and choreoathetosis by direct sequencing. In particular, we characterize the genotype–phenotype correlation between age at onset and the types of <i>PRRT2</i> mutations in all published cases. <b>Results:</b> Direct sequencing showed that 12 out of the 51 families had three different pathogenic mutations (c.649dupC, c.776dupG, c.649C&gt;T) in the <i>PRRT2</i> gene. No significant difference of age at onset between the patients with and without <i>PRRT2</i> mutations was found in this cohort of patients. A total of 97 different <i>PRRT2</i> mutations have been reported in 87 studies till now. The <i>PRRT2</i> mutation classes are wide, and most mutations are frameshift mutations but the most common mutation remains c.649dupC. Comparisons of the age at onset in paroxysmal kinesigenic dyskinesia or infantile convulsions patients with different types of mutations showed no significant difference. <b>Conclusions:</b> This study expands the clinical and genetic spectrums of Chinese patients with paroxysmal kinesigenic dyskinesia and infantile convulsions and choreoathetosis. No clear genotype–phenotype correlation between the age at onset and the types of mutations has been determined.