Abstracts

Rationale: Both PCDH19-related epilepsy and SCN1A-related Dravet syndrome (DS) can cause early onset epileptic encephalopathies characterized by fever provoked seizures. Here, we identified differential clinical and neurodevelopmental characteristics between the two conditions. Methods: Of total, 85 patients who diagnosed with PCDH19-related epilepsy or SCN1A-related DS confirmed by Next Generation Sequencing (NGS) or Sanger sequencing at the Severance Children’s Hospital from January 2005 to March 2019. Following variables were assessed: gender, age of seizure onset, head circumference, occurrence of status epilepticus, period of seizure freedom and seizure types. Neurodevelopmental tests were performed with 41 patients of 85 patients: 7 with PCDH19-related epilepsy; 34 with DS. Neurodevelopment was assessed using Bayley Scales of Infant Development-Ⅱ under 6 years of age; Korean-Wechsler Intelligence Scale for Children (K-WISC) from 6 to 10 years. Bayley Scales of Infant Development-Ⅱ includes 2 sub scales (a) mental development index (MDI) (b) physical development index (PDI); K-WISC includes (a) intelligence quotient (IQ) (b) verbal comprehension index (VCI) (c) perceptual reasoning index (PRI) (d) processing speed index (PSI) (d) working memory index (WMI). Social Maturity Scale (SMS; SQ) was performed. Results: All patients with PCDH19 mutations-related epilepsy were female (11/11). Of 74 patients who had SCN1A, 44 were male. Status epilepticus (9.1% vs. 62.2%, p-value=0.001), focal seizures (9.1% vs. 74.3%, p-value<0.001) and myoclonic seizures (0.0% vs. 40.5%, p-value=0.009) were more commonly identified in patients with SCN1A mutations while clusters of febrile seizures (72.7 % vs. 14.9%, p-value<0.001) were more commonly found in patients with PCDH19 mutations. Median value of maximum period of seizure freedom was longer in patients with PCDH19 mutations than in patients with SCN1A mutation (13.0 [19.25] vs. 2.0 [6.25] months, p-value=0.039). There were no difference in a median age at seizure onset (11.0 [11.25] vs. 6.0 [4.25] months, p-value=0.139). Three PCDH19 patients and 19 DS patients underwent Bayley Scales of Infant Development-Ⅱ; 4 PCDH19 patients and 15 DS patients underwent K-WISC. On K-WISC test, PCDH19 patients got higher scores than DS patients in IQ (71.5 ± 14.5 vs. 48.1 ± 15.6, p-value=0.037), VCI (78.0 ± 9.1 vs. 57.6 ± 14.5, p-value=0.009), PRI (76.5 ± 10.8 vs. 51.6 ± 17.1, p-value=0.008), and WMI (77.5 ± 24.9 vs. 51.9 ± 10.0, p-value=0.004). On Bayley Scales of Infant Development-Ⅱ test, there was no difference in MDI (p-value=0.722), PDI (p-value=0.4445), PSI (73.8 ± 21.8 vs. 56.9 ± 12.7, p-value=0.222) and SQ (78.3 ± 16.9 vs. 67.9 ± 26.1, p-value=0.207) between PCDH19 patients and DS patients. Conclusions: The severity and type of seizures differ between the two conditions. Seizures are longer and more pleomorphic in patients with DS than in patients with PCDH19. Patients with PCDH19 showed better neurodevelopmental test results in IQ, VCI, PRI and WMI than patients with DS and the difference increased after the age of 6 years. Funding: No funding