Missense mutations of the proline-rich transmembrane protein 2 gene cosegregate with mild paroxysmal kinesigenic dyskinesia and infantile convulsions in a Chinese pedigree

Paroxysmal kinesigenic dyskinesia is an autosomal dominant dystonia induced by sudden voluntary movements. Recently, proline-rich transmembrane protein 2 (PRRT2) gene mutations, especially frameshift mutations, were described for PKD. In our study, we have collected a three-generation paroxysmal kinesigenic dyskinesia-infantile convulsions pedigree in Tianjin, North China. The symptoms of six patients varied; age of onset decreased in each generation. Mutations in the PRRT2 gene in nine PKD family members were screened by PCR sequencing of genomic DNA samples. Missense mutations of the PRRT2 gene were found in all four PKD patients and two children with infantile convulsions. All six individuals carried heterozygous codon 138 (Pro/Ala) and codon 306 (Ala/Asp) mutations. Missense mutations of the PRRT2 gene other than truncate and frameshift mutations were account for PKD and/or infantile convulsions. Age of onset and symptoms were not necessarily associated with PRRT2 mutations.