Analysis of a novel frame-shift mutation of PRRT2 gene in a pedigree with paroxysmal kinesigenic dyskinesia

Objective To analyze the clinical data of a patient with paroxysmal kinesigenic dyskinesia (PKD) and his family members and the gene expression of proline-rich transmembrane protein 2 (PRRT2), and to explore the possible pathogenesis of PKD. Methods The clinical data of the family members was collected and the PRRT2 genes of the proband and core family members were analyzed by Sanger sequencing. Results In the pedigree, the proband met the clinical diagnosis standards of PKD, while his uncle had suffered from "epilepsy" in childhood and recovered after 7 years old; and his cousin presented "convulsion" in his infancy. The genetic test results showed a frame-shift mutation c.498delC (p.Thr167Profs^*9) in the PRRT2 gene of the proband and his mother with normal phenotype. At present, such a mutation has not been reported in the Human Gene Mutation Database, which is a novel mutation site. Conclusions The symptoms of PKD in this proband is related to c.498delC mutation of the PRRT2 gene. There may be different or even normal phenotypes in the same family, due to incomplete penetrance of the gene. It is speculated that c.498delC mutation results in the truncated protein of PRRT2 gene, which affects the transmembrane region of the protein.