Clinical and polygraphic study of familial paroxysmal kinesigenic dyskinesia with PRRT2 mutation

Background. Paroxysmal kinesigenic dyskinesia is a neurological condition characterised by brief attacks of involuntary movements triggered by sudden voluntary movements. Methods. We describe the clinical, polygraphic, and genetic features of an Italian family with paroxysmal kinesigenic dyskinesia. Results. Paroxysmal kinesigenic dyskinesia manifested as brief choreoathetosic-dystonic attacks precipitated by sudden movements, varying in severity and frequency, amongst the four affected family members. The disorder follows an autosomal dominant transmission and affects female members. Mutation of SLC2A1, MR1, CACNA1A, and ATP1A2 genes was excluded by direct sequencing. Mutation analysis of the PRRT2 gene revealed a single nucleotide duplication, c.649dupC, resulting in the frameshift mutation p.Arg217Profs*8 in all affected members. Conclusion. Paroxysmal kinesigenic dyskinesia is the most common type of paroxysmal movement disorder and is often misdiagnosed clinically as epilepsy.We describe a family with paroxysmal kinesigenic dyskinesia associated with PRRT2 gene mutation, mild intrafamilial clinical heterogeneity, and benign course.