Mutation analysis of PRRT2 in two Chinese BFIS families and nomenclature of PRRT2 related paroxysmal diseases.

Benign familial infantile seizure (BFIS) and paroxysmal kinesigenic dyskinesia (PKD) are autosomal-dominant inherited self-limited neurological disorders. BFIS is characterized by clusters of epileptic seizures in infancy while, in some cases, infantile seizures and adolescent-onset paroxysmal kinesigenic choreoathetosis co-occurred, which is called infantile convulsions and choreoathetosis (ICCA) syndrome. We and other researchers have reported the proline-rich transmembrane protein 2 (PRRT2) as the causative gene of PKD. We and our collaborators also identified PRRT2 mutations in ICCA and other phenotypes. Here we collected two BFIS families of Chinese Han origin. The linkage analysis has mapped the BFIS-causing locus to 16p12.1-q12.2, where PRRT2 is located. We then performed mutation analysis of PRRT2 by direct sequencing and identified c.649-650insC mutation in all BFIS patients. We also noticed that paroxysmal diseases (such as BFIS, PKD and ICCA) with PRRT2 mutations, instead of other forms, share some characteristics like being responded well to anti-epiletic treatment, we thus suggest to name them as PRRT2-related paroxysmal diseases (PRPDs) in order to assist clinical diagnosis and treatment.