To explore the correlations between phenotypes and genotypes, as well as the extended phenotype spectrum of KCNQ2-related diseases, this study summarized the clinical and genetic characteristics of 30 cases of KCNQ2 mutation in Xiangya Hospital of Central South University in China.

6 likely pathogenic and 24 pathogenic mutations, were found in 30 patients recruited in this study. 20 mutations were previously reported in other studies, while the 10 remaining mutations were novel. 28 mutations were de novo, and 1 novel variant was shown to be inherited from the mother with a BFNS history, for 1 additional cases, parents had not been tested. 30 KCNQ2 mutations were found, including 27 resulted in missense mutation, 2 frameshift mutation and 1 nonsense mutation. Most mutations are located on the C-terminal region and S4 voltage-sensor.

there are four groups, 18 of them presented a severe electroclinical phenotype (EOEE), 5 patientswithout clear classification of epileptic encephalopathy and 6 of them presented a benign phenotype (BNS or BFNS), while the remaining 1 patient was cataloged as Intellectual disability (ID). Age of onset was within the first 1 month of life for 25 patients (83.3%), between 1~6 months of life for 3 patients (10%), beyond 6 months of life for 2 patients (6.7%). The initial seizure types mainly included focal and generalized tonic-clonic, focal and generalized epileptic spasms.

The treatments with sodium channel blockers such as oxcarbazepine, were effective for partial KCNQ2 severe phenotype patients.