Transient hypoglycorrhachia with paroxysmal abnormal eye movement in early infancy.

Paroxysmal abnormal eye movement in early infancy is one of the initial symptoms of glucose transporter 1 deficiency syndrome (GLUT1DS). We describe four early infants with transient hypoglycorrhachia presenting with abnormal eye movements. Their symptoms disappeared after the introduction of a ketogenic diet (KD), and their development was normal. Since no variants in SLC2A1 were detected, the CSF-to-blood glucose ratios (C/B) were re-examined, and within normal range. None of the four patients displayed recurrent symptoms after withdrawal from the KD. Because long-term KD has potential adverse effects and could affect the quality of life of patients and their families, re-examination of CSF glucose during late infancy should be considered in the case of absence of the SLC2A1 pathogenic variant.

MeCP2_e2 partially compensates for lack of MeCP2_e1: A male case of Rett syndrome.

BACKGROUND: Rett syndrome (RTT) is a neurodevelopmental disorder that predominantly affects girls. Its causative gene is the X-linked MECP2 encoding the methyl-CpG-binding protein 2 (MeCP2). The gene comprises four exons and generates two isoforms, namely MECP2_e1 and MECP2_e2. However, it remains unclear whether both MeCP2 isoforms have similar function in the brain. METHODS: We report a case of a boy with typical RTT. Male cases with MECP2 variants have been considered inviable, but somatic mosaicism of the variants can cause RTT in males. Whole-exome sequencing was performed to search for the genetic background. RESULTS: A novel nonsense and mosaic variant was identified in exon 1 of MECP2, and the variant allele fraction (VAF) was 28%. Our patient had the same level of VAF as that in reported male cases with mosaic variants in MECP2 exon 3 or 4, but manifested RTT symptoms that were milder in severity compared to those in these patients. CONCLUSION: This is probably because the variants in MECP2 exon 3 or 4 disrupt both isoforms of MeCP2, whereas the variant in exon 1, as presented in this study, disrupts only MeCP2_e1 but not MeCP2_e2. Therefore, our findings indicate that MeCP2_e2 may partially compensate for a deficiency in MeCP2_e1.

Retigabine, a Kv7.2/Kv7.3-Channel Opener, Attenuates Drug-Induced Seizures in Knock-In Mice Harboring Kcnq2 Mutations.

The hetero-tetrameric voltage-gated potassium channel Kv7.2/Kv7.3, which is encoded by KCNQ2 and KCNQ3, plays an important role in limiting network excitability in the neonatal brain. Kv7.2/Kv7.3 dysfunction resulting from KCNQ2 mutations predominantly causes self-limited or benign epilepsy in neonates, but also causes early onset epileptic encephalopathy. Retigabine (RTG), a Kv7.2/ Kv7.3-channel opener, seems to be a rational antiepileptic drug for epilepsies caused by KCNQ2 mutations. We therefore evaluated the effects of RTG on seizures in two strains of knock-in mice harboring different Kcnq2 mutations, in comparison to the effects of phenobarbital (PB), which is the first-line antiepileptic drug for seizures in neonates. The subjects were heterozygous knock-in mice (Kcnq2Y284C/+ and Kcnq2A306T/+) bearing the Y284C or A306T Kcnq2 mutation, respectively, and their wild-type (WT) littermates, at 63-100 days of age. Seizures induced by intraperitoneal injection of kainic acid (KA, 12mg/kg) were recorded using a video-electroencephalography (EEG) monitoring system. Effects of RTG on KA-induced seizures of both strains of knock-in mice were assessed using seizure scores from a modified Racine's scale and compared with those of PB. The number and total duration of spike bursts on EEG and behaviors monitored by video recording were also used to evaluate the effects of RTG and PB. Both Kcnq2Y284C/+ and Kcnq2A306T/+ mice showed significantly more KA-induced seizures than WT mice. RTG significantly attenuated KA-induced seizure activities in both Kcnq2Y284C/+ and Kcnq2A306T/+ mice, and more markedly than PB. This is the first reported evidence of RTG ameliorating KA-induced seizures in knock-in mice bearing mutations of Kcnq2, with more marked effects than those observed with PB. RTG or other Kv7.2-channel openers may be considered as first-line antiepileptic treatments for epilepsies resulting from KCNQ2 mutations.

Efficacy of antiepileptic drugs for the treatment of Dravet syndrome with different genotypes.

OBJECTIVE: Evaluation of the efficacy of antiepileptic drugs (AEDs) used in the treatment of Dravet syndrome (DS) with different genotypes. METHODS: Patients with DS were recruited from different tertiary hospitals. Using a direct sequencing method and Multiplex Ligation-Dependent Probe Amplification (MLPA), genetic abnormalities were assessed within the exons and flanking introns of SCN1A gene, which encodes the α1 subunit of neuronal sodium channels. Patients were divided into SCN1A-positive and SCN1A-negative groups according to the results of genetic tests. Medical records, including detailed treatment information, were surveyed to compare the effect of different AEDs on clonic or tonic-clonic seizures (GTCS). Efficacy variable was responder rate with regard to seizure reduction. RESULTS: One hundred and sixty of 276 (57.97%) patients had mutation in SCN1A gene (only 128 of them had provided detailed medical records). Among the 116 patients without SCN1A mutations, 87 had provided detailed medical records. Both older AEDs (valproate, phenobarbital, bromide, carbamazepine, clonazepam, and clobazam) and newer AEDs such as zonisamide were used in these patients. Valproate was the most frequently used AED (86.72% in the SCN1A-positive group, 78.16% in the SCN1A-negative group), with 52.25% and 41.18% responder rates in SCN1A-positive and SCN1A-negative patients, respectively (P=0.15). Bromide was used in 40.63% of the SCN1A-positive patients and 20.69% of the SCN1A-negative patients, and its responder rates were 71.15% and 94.44% in SCN1A-positive and SCN1A-negative patients, respectively (P=0.05). Efficacy rates of clonazepam, clobazam, phenobarbital, and zonisamide ranged from 30% to 50%, and these rates were not correlated with different genotypes (P>0.05). Carbamazepine had either no effect or aggravated seizures in all SCN1A-positive patients. SIGNIFICANCE: Bromide is most effective and is a well-tolerated drug among DS patients, especially among SCN1A-negative patients. Carbamazepine should be avoided in patients with SCN1A mutations.

Development of a mouse model of infantile spasms induced by N-methyl-D-aspartate.

Using N-methyl-D-aspartate (NMDA) injection, we attempt to develop a mouse model for infantile spasms (IS). Experiments were performed in postnatal 11- to 13-day-old C57 and Balbc mice. In the pilot experiment, mice were injected with different doses of NMDA (7, 15, and 30 mg/kg) to determine the optimal age and convulsant doses of NMDA. In further experiment optimal age mice were divided into five groups: group A, control group that received intraperitoneal injection of physiological saline; group B, convulsion group that was given intraperitoneal NMDA; group C, pretreatment group that received adrenocorticotropin (ACTH) injection (100 IU/kg) 30 min before NMDA administration; group D, electroencephalogram (EEG) group that received EEG recording, group E, performance group that received motor and learning test at different time point after NMDA administration. The behaviors of each group were observed continuously for 3h, the latency and the total numbers of spasms were recorded. Pilot experiments showed that a 15 mg/kg dose of NMDA could induce typical spasm-like seizures in P13 C57 mice, NMDA administration caused anxiety and deficits in motor and cognitive functions at early time and that large doses of ACTH reduced the number of seizures and rating scale (P<0.05). The NMDA mouse model has the following characteristics: age dependency, spasm-like seizures, cognitive impairment and response to ACTH, which fulfills the criteria of an IS model.

Immediate suppression of seizure clusters by corticosteroids in PCDH19 female epilepsy.

PURPOSE: The pathomechanism and treatment of PCDH19 female epilepsy (PCDH19-FE) remain unclear. Here, we report that corticosteroids are effective for control of the seizure clusters or other acute symptoms of PCDH19-FE and argue for the possible involvement of a compromised blood-brain barrier (BBB) in its pathogenesis. METHODS: The efficacy of corticosteroids was retrospectively reviewed in five Japanese patients with PCDH19-FE. The results of antibody assays against the N-methyl-d-aspartate-type glutamate receptor (abs-NR) in serum/cerebrospinal fluid were also compiled. RESULTS: Corticosteroid treatments significantly improved the acute symptoms, including seizure clusters, in all cases, most often immediately after the initial administration. However, the effect was transient, and some seizures recurred within a few weeks, especially in association with fever. Serum and/or cerebrospinal fluid abs-NR were detected in all patients. Target sequences of the detected antibodies were multiple, and the titers tended to decrease over time. In one patient, immunohistochemical analysis using rat hippocampal slices also revealed serum antibodies targeting an unknown epitope in neuronal cytoplasm. CONCLUSION: Our findings imply an involvement of inflammatory processes in the pathogenesis of PCDH19-FE and therapeutic utility for corticosteroids as an adjunctive option in acute treatment. PCDH19 is well expressed in brain microvascular endothelial cells and thus its impairment may cause BBB vulnerability, which may be ameliorated by corticosteroids. The abs-NR detected in our patients may not indicate an autoimmune pathomechanism, but may rather represent non-specific sensitization to degraded neuronal components entering the general circulation, the latter process facilitated by the BBB vulnerability.

The kick-in system: a novel rapid knock-in strategy.

Knock-in mouse models have contributed tremendously to our understanding of human disorders. However, generation of knock-in animals requires a significant investment of time and effort. We addressed this problem by developing a novel knock-in system that circumvents several traditional challenges by establishing stem cells with acceptor elements enveloping a particular genomic target. Once established, these acceptor embryonic stem (ES) cells are efficient at directionally incorporating mutated target DNA using modified Cre/lox technology. This is advantageous, because knock-ins are not restricted to one a priori selected variation. Rather, it is possible to generate several mutant animal lines harboring desired alterations in the targeted area. Acceptor ES cell generation is the rate-limiting step, lasting approximately 2 months. Subsequent manipulations toward animal production require an additional 8 weeks, but this delimits the full period from conception of the genetic alteration to its animal incorporation. We call this system a "kick-in" to emphasize its unique characteristics of speed and convenience. To demonstrate the functionality of the kick-in methodology, we generated two mouse lines with separate mutant versions of the voltage-dependent potassium channel Kv7.2 (Kcnq2): p.Tyr284Cys (Y284C) and p.Ala306Thr (A306T); both variations have been associated with benign familial neonatal epilepsy. Adult mice homozygous for Y284C, heretofore unexamined in animals, presented with spontaneous seizures, whereas A306T homozygotes died early. Heterozygous mice of both lines showed increased sensitivity to pentylenetetrazole, possibly due to a reduction in M-current in CA1 hippocampal pyramidal neurons. Our observations for the A306T animals match those obtained with traditional knock-in technology, demonstrating that the kick-in system can readily generate mice bearing various mutations, making it a suitable feeder technology toward streamlined phenotyping.

Early onset and focal spike discharges as indicators of poor prognosis for myoclonic-astatic epilepsy.

BACKGROUND: Myoclonic-astatic epilepsy (MAE) is an epileptic syndrome characterized by unique myoclonus, myoclonic-astatic, or astatic seizures in childhood. MAE prognosis vary from spontaneous remission to intractable seizures with profound mental retardation. AIM: Identifying early risk factors may optimize the treatment of children with MAE. Our hypothesis is early onset age and focal spike discharges on EEG indicate a poor MAE prognosis. METHODS: Using the medical records of 9 children with MAE, we analyzed their clinical histories, EEG findings, and seizure symptoms. All patients were given follow-up observations/treatments by our department for at least 2 years after MAE onset. RESULTS: Five of the patients were given favorable prognoses because their seizures disappeared within 2 years of onset; the other 4 received poor prognoses because their seizures continued more than 2 years. MAE onset in patient with refractory seizures was earlier than that in those with a favorable prognosis (7-24 months vs. 23-38 months). All the patients with refractory seizures showed moderate or severe mental retardation. Among the 5 patients with good prognosis, EEGs showed two with focal spike discharges and three with only generalized spike discharges. In contrast, all cases with a poor prognosis had focal spike discharges. CONCLUSIONS: MAE onset in patients with refractory seizures occurs earlier than in those with favorable prognosis. Prognosis was excellent when EEG findings show no focal spike discharges. Both early seizure onset and the focal spike discharges associated with MAE are indicators of poor prognosis.

PCDH19-related female-limited epilepsy: further details regarding early clinical features and therapeutic efficacy.

Abnormalities in the protocadherin 19 (PCDH19) gene cause early-onset epilepsy exclusively in females. We aimed to explore the genetic and clinical characteristics of PCDH19-related epilepsy by focusing on its early features and treatment efficacy. PCDH19 was analyzed in 159 Japanese female patients with early-onset epilepsy via direct sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis. We identified 17 patients with PCDH19 abnormalities: point mutations were observed in 14 patients and whole PCDH19 deletions were detected in 3 patients. One affected sister of a proband with a mild phenotype was also analyzed. The frequency of PCDH19 deletion among all probands identified in Japan was 12.5% (3/24, including 7 probands reported previously by us). Clinical features included early onset (mean age at onset, 8.6 months), recurrent clusters of brief seizures (17/18), fever sensitivity (18/18), tonic seizures (13/18, probably including focal tonic seizures), tonic-clonic seizures (8/18), focal seizures often with subsequent generalization (17/18), intellectual disabilities (15/18), and autistic traits (13/18). Three patients exhibited delay in motor milestones before seizure onset. In 16 patients, seizures appeared in clusters from the onset of the disease. Among 6 patients for whom detailed information at onset was available, 2 onset patterns were identified: a biphasic course of short seizure clusters (each within days) in 2 patients and a prolonged course of clusters (from weeks to a month) in 4 patients. In both cases, initial seizures started during fever and transiently disappeared with the decline of fever; however, afebrile clusters recurred. In the former patients, motor development was delayed before onset, and seizures appeared in strong clusters from the onset of the disease. In the latter patients, initial development was normal and initial seizures were mild, but were followed by strong clusters lasting several weeks, even without fever. Treatment using phenytoin, potassium bromide, and clobazam showed high efficacy. Although focal seizures were the main feature in PCDH19-epilepsy, the efficacy of carbamazepine was poor. This study highlighted the significance of PCDH19 deletion, a unique pattern of initial seizure clusters, and the efficacy of antiepileptic drugs. Our data will facilitate early diagnosis and development of a treatment strategy for better clinical management of patients with PCDH19-related epilepsy.

Diagnosing nocturnal frontal lobe epilepsy: a case study of two children.

We describe two children of nocturnal frontal lobe epilepsy (NFLE) diagnosed using carefully observed nocturnal sleep EEGs and detailed patient histories. Case #1, a 14-year-old boy, showed repeated generalized tonic convulsions and frequent eyes opening seizures during sleep. Conventional EEGs - done with the patient awake or in sleep stage I - showed no abnormalities, while a nocturnal sleep EEG - done during in sleep stage II - revealed the repeated, sharp wave bursts predominantly in the right frontal lobe characteristic of NFLE. During these wave bursts, we noticed the boy's eyes opening, although his parents had not been aware this NFLE symptom. Case #2, a 12-year-old boy, showed one daytime generalized convulsion. He had also been suffering from repeated paroxysmal episodes similar to parasomnia - waking up, sitting, walking, screaming, and speaking - which always followed the same patterns lasting several minutes. During the nocturnal sleep EEG, episodes occurred twice, showing abnormal epileptic discharges predominantly in the frontal lobe. His parents did not mention the episodes to us until questioned, as they had recognized them as parasomnia. The previous conventional EEG showed abnormal slow waves in the frontal lobe, which led us to suspect frontal lobe epilepsy and to take a detailed patient history. The frequency and stereotypy of their symptoms during sleep caused us to perform nocturnal sleep EEGs and led us NFLE diagnosis. Detailed patient histories including sleep habits and carefully observed nocturnal sleep EEGs enabled us to recognize these NFLE clinical features.

Early-onset absence epilepsy at eight months of age.

Early-onset absence epilepsy refers to patients with absence seizures beginning before age four and comprises a heterogeneous group of epilepsies. Onset of absence seizures in the first year of life is very rare. We report a girl with intractable absence seizures with onset at age eight months. Her seizures were characterised by loss of responsiveness, with eyes drifting upwards and some myoclonic jerks of the upper and lower limbs. These symptoms were accompanied by bilaterally symmetric high-amplitude 2-2.5 Hz generalised spike-and-wave discharges on the electroencephalogram. Her seizures were refractory to conventional antiepileptic drugs; treatment with adrenocorticotropic hormone was transiently effective. Comprehensive metabolic screening, cytogenetic, and genetic analysis did not determine an underlying cause of her condition. Patients with intractable, very early-onset absence epilepsy with a myoclonic component have an unfavourable outcome and may be classified under a new epileptic syndrome, such as "early infantile absence epilepsy".