A novel frameshift mutation of PRRT2 in a family with infantile convulsions and choreoathetosis syndrome: c.640delinsCC (p.Ala214ProfsTer11)

The infantile convulsions and choreoathetosis (ICCA) syndrome is defined when two overlapping clinical features of benign familial infantile epilepsy (BFIE) and paroxysmal kinesigenic dyskinesia (PKD) are present in an individual or a family. Since the gene encoding proline-rich transmembrane protein 2 (PRRT2) was first identified in Han Chinese families with PKD, mutations of PRRT2 have additionally been reported in patients with BFIE and ICCA. We attempted to identify the genetic etiology in an ICCA family where the proband, her elder sister, and a maternal male cousin had BFIE, and her mother had PKD. Whole-exome sequencing performed in the proband and her sister and mother identified a novel pathogenic mutation of PRRT2 (c.640delinsCC; p.Ala214ProfsTer11), which was verified by Sanger sequencing. This frameshift PRRT2 mutation located near the genetic hot spot of base 649_650 results in the premature termination of the protein, as do most previously reported mutations in BFIE, ICCA, and PKD.