Mutations in the proline-rich transmembrane protein 2 (PRRT2) gene cause a wide spectrum of neurological diseases, ranging from paroxysmal kinesigenic dyskinesia (PKD) to mental retardation and epilepsy. Previously, seven PKD-related PRRT2 heterozygous mutations were identified in the Taiwanese population: P91QfsX, E199X, S202HfsX, R217PfsX, R217EfsX, R240X and R308C. This study aimed to investigate the disease-causing mechanisms of these PRRT2 mutations. We first documented that Prrt2 was localized at the pre- and post-synaptic membranes with a close spatial association with SNAP25 by synaptic membrane fractionation and immunostaining of the rat neurons. Our results then revealed that the six truncating Prrt2 mutants were accumulated in the cytoplasm and thus failed to target to the cell membrane; the R308C missense mutant had significantly reduced protein expression, suggesting loss-of function effects generated by these mutations. Using in utero electroporation of shRNA into cortical neurons, we further found that knocking down Prrt2 expression in vivo resulted in a delay in neuronal migration during embryonic development and a marked decrease in synaptic density after birth. These pathologic effects and novel disease-causing mechanisms may contribute to the severe clinical symptoms in PRRT2–related diseases.

Summary:  Purpose: To investigate antiepileptic drug (AED) withdrawal during video‐EEG monitoring in adult patients with temporal lobe epilepsy (TLE). Methods: Between 1995 and 1997, 102 consecutive patients with refractory TLE were admitted to the epilepsy monitoring unit for presurgical evaluation. Patients were monitored with ongoing AEDs being rapidly decreased and discontinued in 4–6 days. The monitoring was continued until sufficient numbers of seizures were recorded. Serum AED levels were checked at admission and after the first complex partial seizure (CPS). Results: In all, 89 patients had 429 CPSs (mean, 4.8 per patient), including 156 (36.4%) secondarily generalized. A mean of 153.8 h (16–451 h) was required for completing the monitoring in each patient. Forty‐three (48.3%) patients experienced seizure clusters, and eight (9.0%) had generalized seizures that had never occurred or had been absent for years. However, none evolved to status epilepticus. Carbamazepine was the most commonly used AED in 71.9% of patients, followed by valproate and phenytoin. When the first CPS occurred, mean 77.2 h since the beginning of the monitoring, serum levels of these three AEDs were mostly subtherapeutic rather than minimal. Conclusions: Acute AED withdrawal effectively provoked seizures in TLE patients undergoing presurgical video‐EEG monitoring. However, nearly 50% of patients had seizure clusters or secondarily generalized seizures. Serum AED levels were mostly subtherapeutic when the first CPS occurred.

SUMMARYObjective: This study aimed to explore the effects of theory of mind (ToM) and related potential risk factors, including cognitive functions, psychiatric status, and seizure-related clinical variables, on social functioning in patients with temporal lobe epilepsy (TLE). Methods: Sixty-seven patients with intractable TLE who were potential candidates for epilepsy surgery and 30 matched controls were included. All participants completed four tasks measuring different levels of ToM (False Belief, Faux Pas Recognition, Implication Stories, and Visual Cartoon), the Symptom Checklist-90-Revised (SCL-90-R), the Social and Occupational Functioning Scale for Epilepsy (SOFSE), and neuropsychological tests. Results: The patients exhibited impairments in both basic and advanced ToM. Multiple regression analyses revealed the following: (1) the SOFSE total score was significantly predicted by the Faux Pas Recognition (FPR), Global Severity Index (GSI) score of the SCL-90-R, and Full-Scale intelligence quotient (IQ) of the Wechsler Adult Intelligence Scale (WAIS), which accounted for 38%, 11%, and 8% of the variance, respectively; and (2) the FPR was a significant predictor of all SOFSE subscales, whereas the GSI score contributed substantially to the Interpersonal Relationships, Communication, and Occupation subscales of the SOFSE. Significance: Advanced ToM, measured by impaired faux pas recognition, is a relatively strong predictor of poor social functioning in surgical candidates for intractable TLE. Identifying ToM impairment may help plan nonpharmacologic treatment for improving social functions in patients with intractable TLE.

Mutations in genes involved in the production, migration, or differentiation of cortical neurons often lead to malformations of cortical development (MCDs). However, many genetic mutations involved in MCD pathogenesis remain unidentified. Here we developed a genetic screening paradigm based on transposon-mediated somatic mutagenesis by in utero electroporation and the inability of mutant neuronal precursors to migrate to the cortex and identified 33 candidate MCD genes. Consistent with the screen, several genes have already been implicated in neural development and disorders. Functional disruption of the candidate genes by RNAi or CRISPR/Cas9 causes altered neuronal distributions that resemble human cortical dysplasia. To verify potential clinical relevance of these candidate genes, we analyzed somatic mutations in brain tissue from patients with focal cortical dysplasia and found that mutations are enriched in these candidate genes. These results demonstrate that this approach is able to identify potential mouse genes involved in cortical development and MCD pathogenesis.

Summary:Purpose: To investigate antiepileptic drug (AED) withdrawal during video-EEG monitoring in adult patients with temporal lobe epilepsy (TLE).Methods: Between 1995 and 1997, 102 consecutive patients with refractory TLE were admitted to the epilepsy monitoring unit for presurgical evaluation. Patients were monitored with ongoing AEDs being rapidly decreased and discontinued in 4-6 days. The monitoring was continued until sufficient numbers of seizures were recorded. Serum AED levels were checked at admission and after the first complex partial seizure (CPS).Results: In all, 89 patients had 429 CPSs (mean, 4.8 per patient), including 156 (36.4%) secondarily generalized. A mean of 153.8 h (16-451 h) was required for completing the monitoring in each patient. Forty-three (48.3%) patients experienced seizure clusters, and eight (9.0%) had generalized seizures that had never occurred or had been absent for years. However, none evolved to status epilepticus. Carbamazepine was the most commonly used AED in 71.9% of patients, followed by valproate and phenytoin. When the first CPS occurred, mean 77.2 h since the beginning of the monitoring, serum levels of these three AEDs were mostly subtherapeutic rather than minimal.Conclusions: Acute AED withdrawal effectively provoked seizures in TLE patients undergoing presurgical video-EEG monitoring. However, nearly 50% of patients had seizure clusters or secondarily generalized seizures. Serum AED levels were mostly subtherapeutic when the first CPS occurred.