[Phenotypes and PRRT2 mutation analysis in families with benign familial infantile epilepsy]

To study the phenotypes and proline-rich transmembrane protein 2 (PRRT2) mutations in families with benign familial infantile epilepsy (BFIE).

Data of all BFIE probands and their family members were collected from Peking University First Hospital between September 2006 and August 2013. Clinical phenotypes of affected members were analyzed. Genomic DNA was extracted from peripheral blood samples with standard protocol. Mutations in PRRT2 were screened using PCR amplification and Sanger sequencing.

Twenty-nine BFIE families were recruited in this study. In total, 110 family members were affected. The age of seizure onset of these affected members was between 2 and 12 months (median: 4.5 months). All probands presented with clusters of seizures. Two probands had one seizure induced by diarrhea respectively at 25 months and 31 months. In four BFIE families, four family members had a history of febrile seizures. PRRT2 mutations were found in 17 of the 29 (58.6%) BFIE families. Mutation c.649_650insC was detected in 12 of the 17 families with PRRT2 mutations. Mutation c.649delC (p.R217EfsX12) was identified in three families. Mutation c.323_324delCA (p. T108SfsX25) and c.904_ 905insG (p. D302GfsX39) were detected in one family, respectively.

The minimum seizure onset age of affected members in BFIE families was 2 months of age. The seizures often occur in clusters. PRRT2 is the major causative gene of BFIE in Chinese families. Mutation c.649_650insC is the hotspot mutation of PRRT2. A novel mutation c.323_324delCA was first reported in BFIE family. Few affected members with PRRT2 mutation presented with febrile seizures phenotype.