Clinical and genetic analysis of a Chinese pedigree affected with benign familial neonatal convulsion

Abstract

To analyze the clinical phenotype and genetic variant in a Chinese pedigree affected with benign familial neonatal convulsion (BFNC). Clinical data and peripheral blood samples of the pedigree were obtained with informed consent. Whole exome sequencing (WES) was carried out for the proband. Candidate variants were verified by Sanger sequencing. The pedigree comprised 9 individuals, among whom 4 were affected, including 3 males and 1 female. All patients had developed seizures during the neonatal period, which had ceased in 4 to 6 months. One patient had recurrence in between 1 and 2 years old. Genetic testing has identified a novel nonsense c.810G>A (p.W270X) variant in exon 5 of the KCNQ2 gene, which has co-separated with the BFNC phenotype in the pedigree. The patients from this pedigree have conformed to the diagnosis of BFNC with good prognosis, which was in keeping with previously reported cases. The heterozygous c.810G>A (p.W270X) nonsense variant of the KCNQ2 gene probably underlay the pathogenesis of BFNC in this pedigree, which has expanded the mutational spectrum of the disease.