Steffen Syrbe

De novo loss- or gain-of-function mutations in KCNA2 cause epileptic encephalopathy.

Epileptic encephalopathies are a phenotypically and genetically heterogeneous group of severe epilepsies accompanied by intellectual disability and other neurodevelopmental features. Using next-generation sequencing, we identified four different de novo mutations in KCNA2, encoding the potassium channel KV1.2, in six isolated patients with epileptic encephalopathy (one mutation recurred three times independently). Four individuals presented with febrile and multiple afebrile, often focal seizure types, multifocal epileptiform discharges strongly activated by sleep, mild to moderate intellectual disability, delayed speech development and sometimes ataxia. Functional studies of the two mutations associated with this phenotype showed almost complete loss of function with a dominant-negative effect. Two further individuals presented with a different and more severe epileptic encephalopathy phenotype. They carried mutations inducing a drastic gain-of-function effect leading to permanently open channels. These results establish KCNA2 as a new gene involved in human neurodevelopmental disorders through two different mechanisms, predicting either hyperexcitability or electrical silencing of KV1.2-expressing neurons.

STXBP1 encephalopathy A neurodevelopmental disorder including epilepsy

Objective: To give a comprehensive overview of the phenotypic and genetic spectrum of STXBP1 encephalopathy (STXBP1-E) by systematically reviewing newly diagnosed and previously reported patients. Methods: We recruited newly diagnosed patients with STXBP1 mutations through an international network of clinicians and geneticists. Furthermore, we performed a systematic literature search to review the phenotypes of all previously reported patients. Results: We describe the phenotypic features of 147 patients with STXBP1-E including 45 previously unreported patients with 33 novel STXBP1 mutations. All patients have intellectual disability (ID), which is mostly severe to profound (88%). Ninety-five percent of patients have epilepsy. While one-third of patients presented with Ohtahara syndrome (21%) or West syndrome (9.5%), the majority has a nonsyndromic early-onset epilepsy and encephalopathy (53%) with epileptic spasms or tonic seizures as main seizure type. We found no correlation between severity of seizures and severity of ID or between mutation type and seizure characteristics or cognitive outcome. Neurologic comorbidities including autistic features and movement disorders are frequent. We also report 2 previously unreported adult patients with prominent extrapyramidal features. Conclusion: De novo STXBP1 mutations are among the most frequent causes of epilepsy and encephalopathy. Most patients have severe to profound ID with little correlation among seizure onset, seizure severity, and the degree of ID. Accordingly, we hypothesize that seizure severity and ID present 2 independent dimensions of the STXBP1-E phenotype. STXBP1-E may be conceptualized as a complex neurodevelopmental disorder rather than a primary epileptic encephalopathy.

Benign infantile seizures and paroxysmal dyskinesia caused by an SCN8A mutation

Benign familial infantile seizures (BFIS), paroxysmal kinesigenic dyskinesia (PKD), and their combination—known as infantile convulsions and paroxysmal choreoathetosis (ICCA)—are related autosomal dominant diseases. PRRT2 (proline‐rich transmembrane protein 2 gene) has been identified as the major gene in all 3 conditions, found to be mutated in 80 to 90% of familial and 30 to 35% of sporadic cases.

Delineating the GRIN1 phenotypic spectrum A distinct genetic NMDA receptor encephalopathy

Objective: To determine the phenotypic spectrum caused by mutations in GRIN1 encoding the NMDA receptor subunit GluN1 and to investigate their underlying functional pathophysiology. Methods: We collected molecular and clinical data from several diagnostic and research cohorts. Functional consequences of GRIN1 mutations were investigated in Xenopus laevis oocytes. Results: We identified heterozygous de novo GRIN1 mutations in 14 individuals and reviewed the phenotypes of all 9 previously reported patients. These 23 individuals presented with a distinct phenotype of profound developmental delay, severe intellectual disability with absent speech, muscular hypotonia, hyperkinetic movement disorder, oculogyric crises, cortical blindness, generalized cerebral atrophy, and epilepsy. Mutations cluster within transmembrane segments and result in loss of channel function of varying severity with a dominant-negative effect. In addition, we describe 2 homozygous GRIN1 mutations (1 missense, 1 truncation), each segregating with severe neurodevelopmental phenotypes in consanguineous families. Conclusions: De novo GRIN1 mutations are associated with severe intellectual disability with cortical visual impairment as well as oculomotor and movement disorders being discriminating phenotypic features. Loss of NMDA receptor function appears to be the underlying disease mechanism. The identification of both heterozygous and homozygous mutations blurs the borders of dominant and recessive inheritance of GRIN1-associated disorders.

A missense mutation in the ZFHX1B gene associated with an atypical Mowat-Wilson syndrome phenotype.

Mowat–Wilson syndrome (MWS) is a rare mental retardation—multiple congenital anomalies syndrome associated with typical facial dysmorphism. Patients can show a variety of other anomalies like short stature, microcephaly, Hirschsprung disease, malformations of the brain, seizures, congenital heart defects and urogenital anomalies. Mutations leading to haploinsufficiency of the ZFHX1B gene have been described as the underlying cause of this condition. We report on the clinical findings in a 2½‐year‐old boy with some aspects out of the MWS‐spectrum in addition to unusual anomalies and a novel missense mutation in the ZFHX1B gene.

Mutations in GABRB3: From febrile seizures to epileptic encephalopathies

Objective: To examine the role of mutations in GABRB3 encoding the β3 subunit of the GABAA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes. Methods: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs. Results: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant β3, together with α5 and γ2s subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations. Conclusions: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.

Knowledge and attitudes of school teachers, preschool teachers and students in teacher training about epilepsy and emergency management of seizures

Problem School and preschool teachers play a key role in the care of children with epilepsy. Yet, data about their knowledge on epilepsy are scarce. Methods Assessment of knowledge and attitudes towards epilepsy in teachers by conducting a questionnaire survey in Leipzig and Blankenburg, Germany, from August 2013 to January 2014. Results 1243 questionnaires were completed by 302 school teachers, 883 preschool teachers, 56 students and two unclassified participants. Of the respondents, 140 (11%) stated to have already been actively involved in an epilepsy emergency situation, another 148 (12%) as observers. Only 214 (17%) of respondents felt sufficiently prepared for an emergency. A rescue medication had already been applied by 79 (6%) of respondents; only 186 respondents (15%) stated they would be willing to administer a prescribed rescue medication under any circumstances. In response to an open-ended question about the most common fatal outcomes of a seizure, status epilepticus and drowning were rarely mentioned. 233 (19%) of respondents assumed that epileptic seizures cannot result in death. 606 (49%) of respondents were concerned about the legal repercussions to an incorrect response to a seizure.129/403 (32%) of teachers with >20 years of professional experience claimed never to have had a child suffering from epilepsy in their care, even though the prevalence of childhood epilepsy indicates that they should. In total, 1066 (86%) respondents expressed a desire to gain more knowledge on epilepsy. Conclusions Training programmes for teachers should be established. Furthermore, a clear legal regulatory framework needs to be set up.

Clinical spectrum and genotype-phenotype associations of KCNA2-related encephalopathies

&NA; Recently, de novo mutations in the gene KCNA2, causing either a dominant‐negative loss‐of‐function or a gain‐of‐function of the voltage‐gated K+ channel Kv1.2, were described to cause a new molecular entity within the epileptic encephalopathies. Here, we report a cohort of 23 patients (eight previously described) with epileptic encephalopathy carrying either novel or known KCNA2 mutations, with the aim to detail the clinical phenotype associated with each of them, to characterize the functional effects of the newly identified mutations, and to assess genotype‐phenotype associations. We identified five novel and confirmed six known mutations, three of which recurred in three, five and seven patients, respectively. Ten mutations were missense and one was a truncation mutation; de novo occurrence could be shown in 20 patients. Functional studies using a Xenopus oocyte two‐microelectrode voltage clamp system revealed mutations with only loss‐of‐function effects (mostly dominant‐negative current amplitude reduction) in eight patients or only gain‐of‐function effects (hyperpolarizing shift of voltage‐dependent activation, increased amplitude) in nine patients. In six patients, the gain‐of‐function was diminished by an additional loss‐of‐function (gain‐and loss‐of‐function) due to a hyperpolarizing shift of voltage‐dependent activation combined with either decreased amplitudes or an additional hyperpolarizing shift of the inactivation curve. These electrophysiological findings correlated with distinct phenotypic features. The main differences were (i) predominant focal (loss‐of‐function) versus generalized (gain‐of‐function) seizures and corresponding epileptic discharges with prominent sleep activation in most cases with loss‐of‐function mutations; (ii) more severe epilepsy, developmental problems and ataxia, and atrophy of the cerebellum or even the whole brain in about half of the patients with gain‐of‐function mutations; and (iii) most severe early‐onset phenotypes, occasionally with neonatal onset epilepsy and developmental impairment, as well as generalized and focal seizures and EEG abnormalities for patients with gain‐ and loss‐of‐function mutations. Our study thus indicates well represented genotype‐phenotype associations between three subgroups of patients with KCNA2 encephalopathy according to the electrophysiological features of the mutations.

Use of complementary and alternative medicine (CAM) by parents in their children and adolescents with epilepsy – Prevelance, predictors and parents' assessment

BACKGROUND The use of complementary and alternative medicine (CAM) is popular. Parents of children suffering from epilepsy may also consider administering CAM to their children. Systematic data about frequency of and motivations for CAM use, however, are scarce. METHODS In a university hospitals neuropaediatric department parents of patients aged 0-18 years suffering from epilepsy were consecutively invited to take part in a structured interview during 4 months in 2014. RESULTS Of the invited parents, 164/165 (99%) agreed to participate. From those, 21/164 (13%) stated that they used CAM in their child. The highest independent predictive value of CAM use was the occurrence of adverse drug events (ADE) of anticonvulsants as judged by parents. Patients affected by ADE had a 5.6 higher chance of receiving CAM compared to patients without ADE. Most commonly used were homeopathy (14/21, 67%) and osteopathy (12/21, 57%). The internet was the most frequently used source of information (14/21, 67%). Of the parents, 10/21 (48%) described positive effects of CAM on seizure frequency, 12/21 (57%) on general condition of their child, and 20/21 (95%) wished to continue CAM for epilepsy therapy. From the non-users of CAM, 91/143 (66%) expressed the desire to learn more about CAM for epilepsy therapy. LIMITATIONS Our study was performed in a university hospital in a large urban city in Eastern Germany. CAM user rates can differ in other parts of Germany and Europe, in other institutions and for chronic diseases other than epilepsy. CONCLUSION The main reason for CAM use was the occurrence of ADE of anticonvulsants. More than half of the parents saw a benefit of CAM for their children. Almost all parents wished to continue CAM use, even those who did not see concrete positive effects.

Wide spectrum of clinical manifestations in children with tuberous sclerosis complex – Follow-up of 20 children

UNLABELLED TSC is a multisystem genetic disorder predisposing to multiple organ manifestations and developmental problems. Clinical follow-up of patients remains a challenge for the caring paediatrician. METHODS We performed a retrospective analysis of clinical manifestations, diagnostic and therapeutic data in 20 children with the diagnosis of tuberous sclerosis complex (TSC) to answer the following questions: are the clinical guidelines and imaging strategies appropriate to discover complications, are there significant early predictors of long-term prognosis, what is the age range for signs and symptoms to occur. RESULTS Cardiac rhabdomyoma were present in 18 children and occurred as earliest manifestation. 8 of these exhibited associated arrhythmia or congenital cardiac anomalies. Seizures combined with cortical tubers and subependymal nodules occurred in 18 patients and were most likely to start in infancy, which was associated with later cognitive impairment. Cutaneous manifestations (15 children) occurred in late childhood and school age, whilst renal angiomyolipomas (11) developed in puberty. DISCUSSION The clinical course and imaging strategies are compared with data from previous studies. A review of TSC in regard to the multiple manifestations is provided.