Marina Trivisano

Genetic and phenotypic heterogeneity suggest therapeutic implications in SCN2A-related disorders

Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p.Arg853Gln: two new and four previously reported children). Other known phenotypes include Ohtahara syndrome, epilepsy of infancy with migrating focal seizures, and intellectual disability or autism without epilepsy. To assess the response to antiepileptic therapy, we retrospectively reviewed the treatment regimen and the course of the epilepsy in 66 patients for which well-documented medical information was available. We find that the use of sodium channel blockers was often associated with clinically relevant seizure reduction or seizure freedom in children with early infantile epilepsies (<3 months), whereas other antiepileptic drugs were less effective. In contrast, sodium channel blockers were rarely effective in epilepsies with later onset (≥3 months) and sometimes induced seizure worsening. Regarding the genetic findings, truncating mutations were exclusively seen in patients with late onset epilepsies and lack of response to sodium channel blockers. Functional characterization of four selected missense mutations using whole cell patch-clamping in tsA201 cells-together with data from the literature-suggest that mutations associated with early infantile epilepsy result in increased sodium channel activity with gain-of-function, characterized by slowing of fast inactivation, acceleration of its recovery or increased persistent sodium current. Further, a good response to sodium channel blockers clinically was found to be associated with a relatively small gain-of-function. In contrast, mutations in patients with late-onset forms and an insufficient response to sodium channel blockers were associated with loss-of-function effects, including a depolarizing shift of voltage-dependent activation or a hyperpolarizing shift of channel availability (steady-state inactivation). Our clinical and experimental data suggest a correlation between age at disease onset, response to sodium channel blockers and the functional properties of mutations in children with SCN2A-related epilepsy.

Spectrum of phenotypes in female patients with epilepsy due to protocadherin 19 mutations.

Purpose:  To describe clinical and neuropsychological features of six consecutive sporadic girls with protocadherin 19 (PCDH19) mutations.

Panayiotopoulos syndrome: A clinical, EEG, and neuropsychological study of 93 consecutive patients

Purpose:  To explore the clinical, electroencephalography (EEG), neuropsychological features, and prognosis of Panayiotopoulos syndrome (PS).

Documentation of autonomic seizures and autonomic status epilepticus with ictal EEG in Panayiotopoulos syndrome.

Panayiotopoulos syndrome (PS) is a common childhood susceptibility to autonomic seizures and status epilepticus. Despite its high prevalence, PS has been a source of significant debate. We present ictal EEG documentation of autonomic seizures and autonomic status epilepticus in six cases of PS and a review of 14 reported cases. Interictal EEGs showed spikes of variable locations that often changed with time. Ictal EEG onsets were also variable, starting from wide anterior or posterior regions usually with theta waves intermixed with small spikes and fast rhythms. Ictal vomiting and other autonomic manifestations, as well as deviation of the eyes, did not appear to relate to any specific region of EEG activation. These data document that PS is a multifocal autonomic epilepsy and support the view that the clinical manifestations are likely to be generated by variable and widely spread epileptogenic foci acting on a temporarily hyperexcitable central autonomic network.

PCDH19-related epilepsy in two mosaic male patients

PCDH19 gene mutations have been recently associated with an epileptic syndrome characterized by focal and generalized seizures. The PCDH19 gene (Xq22.1) has an unusual X‐linked inheritance with a selective involvement for female subjects. A cellular interference mechanism has been hypothesized and male patients can manifest epilepsy only in the case of a mosaicism. So far about 100 female patients, and only one symptomatic male have been described. Using targeted next generation sequencing (NGS) approach we found a PCDH19 point mutation in two male patients with a clinical picture suggestive of PCDH19‐related epilepsy. The system allowed us to verify that the two c.1352 C>T; p.(Pro451Leu) and c.918C>G; p.(Tyr306*) variants occurred in mosaic status. Mutations were confirmed by Sanger sequencing and quantified by real‐time polymerase chain reaction (PCR). Up to now, the traditional molecular screening for PCDH19‐related epilepsy has been targeted to all females with early onset epilepsy with or without cognitive impairment. Male patients were generally excluded. We describe for the first time two mosaic PCDH19 point mutations in two male patients with a clinical picture suggestive of PCDH19‐related epilepsy. This finding opens new opportunities for the molecular diagnoses in patients with a peculiar type of epilepsy that remains undiagnosed in male patients.

Electroencephalographic features in Dravet syndrome: Five-year follow-up study in 22 patients

The aim of the study was to evaluate interictal electroencephalogram features in 22 patients with Dravet syndrome from the onset of the disease through the next 5 years. Electroencephalogram was abnormal in 5 patients (22.7%) at onset, and in 17 (77.3%) at the end of the study. Epileptiform abnormalities (focal, multifocal, or generalized) were seen in 6 patients at the onset and in 14 (27% vs 64%) at the end of the study. Photoparoxysmal response was present in 41% of patients at the end of follow-up. No statistical differences were found between mutated and nonmutated groups regarding evolution of background activity, interictal abnormalities, and presence of photoparoxysmal response. Electroencephalogram findings seemed to be age dependent, variable among different patients, and not influenced by the presence of sodium channel, voltage-gated, type I, alpha subunit (SCN1A) mutation. The lack of specific epileptiform abnormalities contributes to the difficulty of patients’ management in Dravet syndrome.

PRRT2 is mutated in familial and non-familial benign infantile seizures

BACKGROUND Mutations of protein-rich transmembrane protein 2 (PRRT2) were recently associated to benign familial infantile seizures (BFIS) (MIM 605751) and paroxysmal kinesigenic dyskinesias (PKD) (MIM12800). AIMS To report mutations of PRRT2 in BFIS, infantile convulsions and choreoathetosis (ICCA), and in sporadic cases affected by benign infantile epilepsy (BIE). METHODS A mutational screening of PRRT2 was performed in 5 families, and in 7 sporadic cases affected by BIE. All clinical and neurophysiological details were reviewed. RESULTS Thirty-three members among 5 families were collected. Fifteen individuals had infantile seizures and one had infantile seizures followed by paroxysmal kinesigenic dyskinesia (PKD). We found the c.649_650InsC PRRT2 mutation in all tested patients (13 out of 15). Age at onset ranged from 3.5 to 10 months. Focal seizures, with or without secondary generalization, occurred mainly in cluster. One patient at the age of 11 years presented with PKD successfully treated with carbamazepine. All patients had a normal cognitive development. Two out of 7 non-familial cases (28.5%) carried a de novo PRRT2 mutation: the c.649_650InsC mutation in one with clustered seizures at the age of 5 months and an unreported c.718C-T p.R240X mutation in the other who, after cluster focal seizures at the age of 5 months, experienced absences at the age of 5 years. CONCLUSION Our findings emphasize that PRRT2 mutations might be responsible of both BFIS and ICCA, but might be causative also for sporadic cases of benign infantile seizures. The phenotypic spectrum comprises BFIS, ICCA, and PKD.

Childhood refractory focal epilepsy following acute febrile encephalopathy

Background:  We describe a group of previously normal children who developed severe focal epilepsy after an acute/sub‐acute illness resembling encephalitis.

Migraine triggered by epileptic discharges in a Rasmussen's encephalitis patient after surgery.

After 2years from disconnective surgery for Rasmussens encephalitis, a child, 9years old, began to present severe migraine attacks, lateralized to the operated side, lasting 1-2days. Video/EEG recordings during two different migraine attacks, with an interval of 6months from each other, showed, in both recordings, subsequent ictal discharges over the affected and disconnected hemisphere. Migraine and ictal discharges in both occasion disappeared with diazepam i.v. The EEGs performed during migraine-free period, on the contrary, showed very rare and mild subclinical ictal discharges. Although a casual relationship could not be excluded, a pure neuronal pathogenetic mechanism can be suggested, mediated by post- and inter-ictal cortical depression.

Myoclonic astatic epilepsy: An age-dependent epileptic syndrome with favorable seizure outcome but variable cognitive evolution

The objective of the study was to explore clinical, electroencephalography (EEG), neuropsychological features and prognosis of myoclonic-astatic epilepsy (MAE). Of 327 children aged between 1 and 9 years with a diagnosis of generalized epilepsy followed between 2000 and 2008, 18 (5.5%) had MAE. Male significantly predominated (88.9%). Age at onset ranged from 2.3 to 4.9 years (mean 3.6 years). Median follow-up period was 6.3 years. In addition to myoclonic-astatic seizures patients had myoclonic seizures (66.7%), drop attacks (72.2%), head drops (77.8%) absences (88.9%), tonic-clonic generalized seizure (77.8%), tonic seizures (38.9%), non-convulsive status epilepticus (16.7%). Seven patients (38.9%) had an epileptic encephalopathy. At onset, interictal epileptiform and slow abnormalities were recorded, respectively, in 100% and 77.8% of patients. EEG abnormalities disappeared in all patients within 4 years since the onset. At long-term follow-up, two patients developed focal abnormalities typical of rolandic epilepsy and two patients photosensitivity. On neuropsychological testing 66.7% of patients had a normal IQ (mean 81.2±17.0, range 47-105, median 84.5) after a mean period of 4.4 years since the last seizure. Sixteen out of 18 patients remitted within 3.5 years since the onset and in two patients tonic seizures persisted. MAE is generalized childhood epilepsy: although cognitive functions might deteriorate, outcome is good regarding seizures.