[P3-63] A case of non-familial neonatal epilepsy with a novel de novo KCNQ2 mutation
Mutations in KCNQ2 gene have been reported as a cause of benign familial neonatal epilepsy, classically. However, KCNQ2 mutations were recently reported associated with non-familial benign neonatal epilepsy and early infantile epileptic encephalopathy. Here, we show a case of non-familial neonatal epilepsy with a de novo KCNQ2 mutation. The boy was born as the second baby to non-consanguineous Japanese parents after uneventful full-term gestation. No family history of neonatal seizures or epilepsy was noted. From 2 days of age, he developed tonic seizures with cyanosis lasting several tens of seconds. No significant abnormality was detected by means of blood tests, urine analyses, cerebral spinal fluid tests, cranial ultrasound, brain imaging. The ictal electroencephalograms showed focal seizures with variable onsets. Although phenobarbital was administered up to 40mg/kg of cumulative dose, seizures persisted. As a second-line treatment, we administered a loading dose of fosphenytoin (fos-PHT), followed by maintenance doses of fos-PHT every day, then seizures were controlled. However, seizures sometimes recurred when the blood concentration of PHT was subtherapeutic. At 22 days of age, we discontinued fos-PHT and started oral administration of carbamazepine, after that seizures were completely controlled for 7 months. At the age of 8 months, generalized seizures recurred due to medication non-adherence. For investigation of the underlying disorder, genetic testing related to epilepsy was done. A novel de novo missense mutation (c.940T>A, p.Ser314Thr) of KCNQ2 was revealed. We discuss the relationship between the mutation in KCNQ2 and efficacies of sodium channel blockers in this case.