•Different mutations of the HCN channels can predispose to the development of epilepsy.•HCN1 mutations account for the majority of patients, but also the alteration of HCN2 and HCN4 can have a role ...in epilepsy.•Several rare variants of unknown significance (VUS) are found in genes coding for HCN channels and accessory proteins.•It would be wise to include the genetic screening of HCN channels as a standard diagnostic tool for epilepsy.
The Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels are highly expressed in the Central Nervous Systems, where they are responsible for the Ih current. Together with specific accessory proteins, these channels finely regulate neuronal excitability and discharge activity. In the last few years, a substantial body of evidence has been gathered showing that modifications of Ih can play an important role in the pathogenesis of epilepsy. However, the extent to which HCN dysfunction is spread among the epileptic population is still unknown. The aim of this work is to evaluate the impact of genetic mutations potentially affecting the HCN channels’ activity, using a NGS approach. We screened a large cohort of patients with epilepsy of unknown etiology for mutations in HCN1, HCN2 and HCN4 and in genes coding for accessory proteins (MiRP1, Filamin A, Caveolin-3, TRIP8b, Tamalin, S-SCAM and Mint2). We confirmed the presence of specific mutations of HCN genes affecting channel function and predisposing to the development of the disease. We also found several previously unreported additional genetic variants, whose contribution to the phenotype remains to be clarified. According to these results and data from literature, alteration of HCN1 channel function seems to play a major role in epilepsy, but also dysfunctional HCN2 and HCN4 channels can predispose to the development of the disease. Our findings suggest that inclusion of the genetic screening of HCN channels in diagnostic procedures of epileptic patients should be recommended. This would help pave the way for a better understanding of the role played by Ih dysfunction in the pathogenesis of epilepsy.
GLUT1 deficiency syndrome is a rare, genetically determined neurological disorder for which Ketogenic Dietary Treatment represents the gold standard and lifelong treatment. Patient registries are ...powerful tools providing insights and real-world data on rare diseases.
To describe the implementation of a national web-based registry for GLUT1-DS.
This is a retrospective and prospective, multicenter, observational registry developed in collaboration with the Italian GLUT1-DS association and based on an innovative, flexible and configurable cloud computing technology platform, structured according to the most rigorous requirements for the management of patient's sensitive data. The Glut1 Registry collects baseline and follow-up data on the patient's demographics, history, symptoms, genotype, clinical, and instrumental evaluations and therapies.
Five Centers in Italy joined the registry, and two more Centers are currently joining. In the first two years of running, data from 67 patients (40 females and 27 males) have been collected. Age at symptom onset was within the first year of life in most (40, 60%) patients. The diagnosis was formulated in infancy in almost half of the cases (34, 51%). Symptoms at onset were mainly paroxysmal (mostly epileptic seizure and paroxysmal ocular movement disorder) or mixed paroxysmal and fixed symptoms (mostly psychomotor delay). Most patients (53, 79%) are currently under Ketogenic dietary treatments.
We describe the principles behind the design, development, and deployment of the web-based nationwide GLUT1-DS registry. It represents a stepping stone towards a more comprehensive understanding of the disease from onset to adulthood. It also represents a virtuous model from a technical, legal, and organizational point of view, thus representing a possible paradigmatic example for other rare disease registry implementation.
Background:
Purified cannabidiol (CBD) was administered to highly refractory patients with Dravet (DS) or Lennox–Gastaut (LGS) syndromes in an ongoing expanded access program (EAP). Herein, we report ...interim results on CBD safety and seizure outcomes in patients treated for a 12-month period.
Material and Methods:
Thirty centers were enrolled from December 2018 to December 2019 within the open-label prospective EAP up to a maximum of 25 mg/kg per day. Adverse effects and liver function tests were assessed after 2 weeks; 1, 3, and 6 months of treatment; and periodically thereafter. Seizure endpoints were the percentage of patients with ≥50 and 100% reduction in seizures compared to baseline.
Results:
A total of 93 patients were enrolled and included in the safety analysis. Eighty-two patients 27 (32.9%) DS, 55 (67.1%) LGS with at least 3 months of treatment have been included in the effectiveness analysis; median previously failed antiseizure medications was eight. Pediatric and adult patients were uniformly represented in the cohort. At 3-month follow-up, compared to the 28-day baseline period, the percentage of patients with at least a 50% reduction in seizure frequency was 40.2% (plus 1.2% seizure-free). Retention rate was similar according to diagnosis, while we found an increased number of patients remaining under treatment in the adult group. CBD was mostly coadministered with valproic acid (62.2%) and clobazam (41.5%). In the safety dataset, 29 (31.2%) dropped out: reasons were lack of efficacy 16 (17.2%) and adverse events (AEs) 12 (12.9%), and one met withdrawal criteria (1.1%). Most reported AEs were somnolence (22.6%) and diarrhea (11.9%), followed by transaminase elevation and loss of appetite.
Conclusions:
CBD is associated with improved seizure control also in a considerable proportion of highly refractory patients with DS and LGS independently from clobazam use. Overall, CBD safety and effectiveness are not dose-related in this cohort.
The objective of this study was to identify developmental trajectories of developmental/behavioral phenotypes and possibly their relationship to epilepsy and genotype by analyzing developmental and ...behavioral features collected prospectively and longitudinally in a cohort of patients with Dravet syndrome (DS).
Thirty-four patients from seven Italian tertiary pediatric neurology centers were enrolled in the study. All patients were examined for the SCN1A gene mutation and prospectively assessed from the first years of life with repeated full clinical observations including neurological and developmental examinations. Subjects were found to follow three neurodevelopmental trajectories. In the first group (16 patients), an initial and usually mild decline was observed between the second and the third year of life, specifically concerning visuomotor abilities, later progressing towards global involvement of all abilities. The second group (12 patients) showed an earlier onset of global developmental impairment, progressing towards a generally worse outcome. The third group of only two patients ended up with a normal neurodevelopmental quotient, but with behavioral and linguistic problems. The remaining four patients were not classifiable due to a lack of critical assessments just before developmental decline.
The neurodevelopmental trajectories described in this study suggest a differential contribution of neurobiological and genetic factors. The profile of the first group, which included the largest fraction of patients, suggests that in the initial phase of the disease, visuomotor defects might play a major role in determining developmental decline.
Early diagnosis of milder cases with initial visuomotor impairment may therefore provide new tools for a more accurate habilitation strategy.
Abstract Aims of our study were to describe the early clinical features of Dravet syndrome (SMEI) and the neurological, cognitive and behavioral outcome. The clinical history of 37 patients with ...clinical diagnosis of SMEI, associated with a point mutation of SCN1A gene in 84% of cases, were reviewed with particular attention to the symptoms of onset. All the patients received at least one formal cognitive and behavior evaluation. Epilepsy started at a mean age of 5.7 months; the onset was marked by isolated seizure in 25 infants, and by status epilepticus in 12; the first seizure had been triggered by fever, mostly of low degree in 22 infants; the first EEG was normal in all cases. During the second year of life difficult-to-treat seizures recurred, mostly triggered by fever, hot bath, and intermittent lights and delay in psychomotor development became evident. At the last evaluation, performed at a mean age of 16 ± 6.9 years, mental retardation was present in 33 patients, associated with behavior disorders in 21. Our data indicate that the most striking features of SMEI are: the early onset of seizures in a previously healthy child, the long duration of the first seizure, the presence of focal ictal symptoms, and sensitivity to low-grade fever. Diagnosis of SMEI may be proposed by the end of the first year of life, and a definite diagnosis can be established during the second year based on the peculiar seizure-favoring factors, EEG photosensitivity and psychomotor slowing. The temporal correlation between high seizure frequency and cognitive impairment support the role of epilepsy in the clinical outcome, even if a role of channelopathy cannot be ruled out.
Over one hundred mutations in the Kv7.2 (KCNQ2) gene encoding for phosphatidylinositol 4,5-bisphosphate (PIP
2
)-sensitive voltage-gated K
+
channel subunits have been identified in early-onset ...epilepsies with wide phenotypic variability. By contrast, only few mutations in the closely related Kv7.3 (KCNQ3) gene have been reported, mostly associated with typical benign familial neonatal seizures (BFNS). We herein describe a patient affected by early onset epileptic encephalopathy (EOEE) carrying two Kv7.3 missense mutations (p.Val359Leu/V359L and p.Asp542Asn/D542N) in compound heterozygosis, each inherited from an asymptomatic parent. Patch-clamp recordings from transiently transfected CHO cells showed that, when incorporated in physiologically relevant Kv7.2 + Kv7.3 heteromeric channels, expression of Kv7.3 V359L or Kv7.3 D542N subunits failed to affect current density, whereas a significant decrease was instead observed when these mutant subunits were both simultaneously present. Modeling and functional experiments revealed that each variant decreased PIP
2
-dependent current regulation, with additive effects when the two were co-expressed. Moreover, expression of Kv7.2 subunits carrying the D535N variant previously described in three sporadic EOEE cases prompted functional changes more dramatic when compared to those of the corresponding D542N variant in Kv7.3, but similar to those observed when both Kv7.3 V359L and Kv7.3 D542N subunits were expressed together. Finally, the Kv7 activator retigabine restored channel dysfunction induced by each Kv7.2 or Kv7.3 variant(s). These results provide a plausible molecular explanation for the apparent recessive inheritance of the phenotype in the family investigated, and a rational basis for personalized therapy with Kv7 channel activators in EOEE patients carrying loss-of-function mutations in Kv7.2 or Kv7.3.
Rolandic epilepsy (RE) is the most common idiopathic focal childhood epilepsy. Its molecular basis is largely unknown and a complex genetic etiology is assumed in the majority of affected ...individuals. The present study tested whether six large recurrent copy number variants at 1q21, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 previously associated with neurodevelopmental disorders also increase risk of RE. Our association analyses revealed a significant excess of the 600 kb genomic duplication at the 16p11.2 locus (chr16: 29.5-30.1 Mb) in 393 unrelated patients with typical (n = 339) and atypical (ARE; n = 54) RE compared with the prevalence in 65,046 European population controls (5/393 cases versus 32/65,046 controls; Fisher's exact test P = 2.83 × 10(-6), odds ratio = 26.2, 95% confidence interval: 7.9-68.2). In contrast, the 16p11.2 duplication was not detected in 1738 European epilepsy patients with either temporal lobe epilepsy (n = 330) and genetic generalized epilepsies (n = 1408), suggesting a selective enrichment of the 16p11.2 duplication in idiopathic focal childhood epilepsies (Fisher's exact test P = 2.1 × 10(-4)). In a subsequent screen among children carrying the 16p11.2 600 kb rearrangement we identified three patients with RE-spectrum epilepsies in 117 duplication carriers (2.6%) but none in 202 carriers of the reciprocal deletion. Our results suggest that the 16p11.2 duplication represents a significant genetic risk factor for typical and atypical RE.
Objective
To determine whether brain volumetric and white matter microstructural changes are present and correlate with neurological impairment in subjects with alternating hemiplegia of childhood ...(AHC).
Methods
In this prospective single-center study, 12 AHC subjects (mean age 22.9 years) and 24 controls were studied with 3DT1-weighted MR imaging and high angular resolution diffusion imaging at 3T. Data obtained with voxel-based morphometry and tract-based spatial statistics were correlated with motor impairment using the International Cooperative Ataxia Rating Scale (ICARS) and Movement and Disability sub-scales of Burke-Fahn-Marsden Dystonia Rating Scale (BFMMS and BFMDS).
Results
Compared to healthy controls, AHC subjects showed lower total brain volume (
P
< 0.001) and white matter volume (
P
= 0.002), with reduced clusters of white matter in frontal and parietal regions (
P
< 0.001). No significant regional differences were found in cortical or subcortical grey matter volumes. Lower cerebellar subvolumes correlated with worse ataxic symptoms and global motor impairment in AHC group (
P
< 0.001). Increased mean and radial diffusivity values were found in the corpus callosum, corticospinal tracts, superior and inferior longitudinal fasciculi, subcortical frontotemporal white matter, internal and external capsules, and optic radiations (
P
< 0.001). These diffusion scalar changes correlated with higher ICARS and BFMDS scores (
P
< 0.001).
Interpretation
AHC subjects showed prevalent white matter involvement, with reduced volume in several cerebral and cerebellar regions associated with widespread microstructural changes reflecting secondary myelin injury rather than axonal loss. Conversely, no specific pattern of grey matter atrophy emerged. Lower cerebellar volumes, correlating with severity of neurological manifestations, seems related to disrupted developmental rather than neurodegenerative processes.
Highlights • Hemispherotomy is treatment of choice in RE but long-term data are not available. • We present long-term outcomes in 16 patients with RE who underwent hemispherotomy. • 13 patients were ...seizure-free; drugs were withdrawn in 10 and reduced in 6. • Early hemispherotomy favors good motor and cognitive outcomes. • Hemispherotomy should be considered early in disease course.
Alternating hemiplegia of childhood is a rare disorder caused by de novo mutations in the ATP1A3 gene, expressed in neurons and cardiomyocytes. As affected individuals may survive into adulthood, we ...use the term 'alternating hemiplegia'. The disorder is characterized by early-onset, recurrent, often alternating, hemiplegic episodes; seizures and non-paroxysmal neurological features also occur. Dysautonomia may occur during hemiplegia or in isolation. Premature mortality can occur in this patient group and is not fully explained. Preventable cardiorespiratory arrest from underlying cardiac dysrhythmia may be a cause. We analysed ECG recordings of 52 patients with alternating hemiplegia from nine countries: all had whole-exome, whole-genome, or direct Sanger sequencing of ATP1A3. Data on autonomic dysfunction, cardiac symptoms, medication, and family history of cardiac disease or sudden death were collected. All had 12-lead electrocardiogram recordings available for cardiac axis, cardiac interval, repolarization pattern, and J-point analysis. Where available, historical and prolonged single-lead electrocardiogram recordings during electrocardiogram-videotelemetry were analysed. Half the cohort (26/52) had resting 12-lead electrocardiogram abnormalities: 25/26 had repolarization (T wave) abnormalities. These abnormalities were significantly more common in people with alternating hemiplegia than in an age-matched disease control group of 52 people with epilepsy. The average corrected QT interval was significantly shorter in people with alternating hemiplegia than in the disease control group. J wave or J-point changes were seen in six people with alternating hemiplegia. Over half the affected cohort (28/52) had intraventricular conduction delay, or incomplete right bundle branch block, a much higher proportion than in the normal population or disease control cohort (P = 0.0164). Abnormalities in alternating hemiplegia were more common in those ≥16 years old, compared with those <16 (P = 0.0095), even with a specific mutation (p.D801N; P = 0.045). Dynamic, beat-to-beat or electrocardiogram-to-electrocardiogram, changes were noted, suggesting the prevalence of abnormalities was underestimated. Electrocardiogram changes occurred independently of seizures or plegic episodes. Electrocardiogram abnormalities are common in alternating hemiplegia, have characteristics reflecting those of inherited cardiac channelopathies and most likely amount to impaired repolarization reserve. The dynamic electrocardiogram and neurological features point to periodic systemic decompensation in ATP1A3-expressing organs. Cardiac dysfunction may account for some of the unexplained premature mortality of alternating hemiplegia. Systematic cardiac investigation is warranted in alternating hemiplegia of childhood, as cardiac arrhythmic morbidity and mortality are potentially preventable.
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