De novo missense variants in FBXO11 alter its protein expression and subcellular localization.

Recently, others and we identified de novo FBXO11 (F-Box only protein 11) variants as causative for a variable neurodevelopmental disorder (NDD). We now assembled clinical and mutational information on 23 additional individuals. The phenotypic spectrum remains highly variable, with developmental delay and/or intellectual disability as the core feature and behavioral anomalies, hypotonia and various facial dysmorphism as frequent aspects. The mutational spectrum includes intragenic deletions, likely gene disrupting and missense variants distributed across the protein. To further characterize the functional consequences of FBXO11 missense variants, we analyzed their effects on protein expression and localization by overexpression of 17 different mutant constructs in HEK293 and HeLa cells. We found that the majority of missense variants resulted in subcellular mislocalization and/or reduced FBXO11 protein expression levels. For instance, variants located in the nuclear localization signal and the N-terminal F-Box domain lead to altered subcellular localization with exclusion from the nucleus or the formation of cytoplasmic aggregates and to reduced protein levels in western blot. In contrast, variants localized in the C-terminal Zn-finger UBR domain lead to an accumulation in the cytoplasm without alteration of protein levels. Together with the mutational data, our functional results suggest that most missense variants likely lead to a loss of the original FBXO11 function and thereby highlight haploinsufficiency as the most likely disease mechanism for FBXO11-associated NDDs.

Reduced Interhemispheric Coherence and Cognition in Children with Fetal Alcohol Spectrum Disorder (FASD)-A Quantitative EEG Study.

BACKGROUND: Magnetic resonance imaging in fetal alcohol spectrum disorder (FASD) children showed altered connectivity, suggesting underlying deficits in networks, which may be related to cognitive outcome. Functional connectivity has been of interest in neurophysiological research with quantitative electroencephalography (QEEG) as useful tool for measuring pathology, not detectable by normal EEG. The aim of this study was to investigate differences in the EEG interhemispheric coherence (ICoh) in children diagnosed with FASD compared with healthy controls and to relate the results to cognitive scores. METHOD: Analysis of ICoh in 81 FASD children (4-Digit Code) compared with 31 controls. The children underwent cognitive assessment, and EEG was performed and used for analysis. Group comparisons and analysis of covariance interaction models were used to test for differences between FASD and controls but also to look for differences between FASD subgroups. Significant findings were correlated to cognitive scores. RESULTS: Lower ICoh was found in the frontal and temporal derivations in the FASD group. When comparing FASD subgroups, children with fetal alcohol syndrome had lower ICoh occipital. Reduced ICoh in the temporal alpha band was correlated with lower performance IQ in the FASD group. CONCLUSION: Our findings could imply hypoconnectivity between the hemispheres with impact on cognition. We suggest that EEG coherence analysis could be a sensitive parameter in the detection of electrophysiological abnormalities in FASD with possible clinical relevance. These results may indicate that QEEG could be used as biomarker for FASD. However, further research is needed to determine the role of QEEG analysis in the diagnosis of FASD.

KCND2 variants associated with global developmental delay differentially impair Kv4.2 channel gating.

Here, we report on six unrelated individuals, all presenting with early-onset global developmental delay, associated with impaired motor, speech and cognitive development, partly with developmental epileptic encephalopathy and physical dysmorphisms. All individuals carry heterozygous missense variants of KCND2, which encodes the voltage-gated potassium (Kv) channel α-subunit Kv4.2. The amino acid substitutions associated with the variants, p.(Glu323Lys) (E323K), p.(Pro403Ala) (P403A), p.(Val404Leu) (V404L) and p.(Val404Met) (V404M), affect sites known to be critical for channel gating. To unravel their likely pathogenicity, recombinant mutant channels were studied in the absence and presence of auxiliary ß-subunits under two-electrode voltage clamp in Xenopus oocytes. All channel mutants exhibited slowed and incomplete macroscopic inactivation, and the P403A variant in addition slowed activation. Co-expression of KChIP2 or DPP6 augmented the functional expression of both wild-type and mutant channels; however, the auxiliary ß-subunit-mediated gating modifications differed from wild type and among mutants. To simulate the putative setting in the affected individuals, heteromeric Kv4.2 channels (wild type + mutant) were studied as ternary complexes (containing both KChIP2 and DPP6). In the heteromeric ternary configuration, the E323K variant exhibited only marginal functional alterations compared to homomeric wild-type ternary, compatible with mild loss-of-function. By contrast, the P403A, V404L and V404M variants displayed strong gating impairment in the heteromeric ternary configuration, compatible with loss-of-function or gain-of-function. Our results support the etiological involvement of Kv4.2 channel gating impairment in early-onset monogenic global developmental delay. In addition, they suggest that gain-of-function mechanisms associated with a substitution of V404 increase epileptic seizure susceptibility.

Mutations in PIGU Impair the Function of the GPI Transamidase Complex, Causing Severe Intellectual Disability, Epilepsy, and Brain Anomalies.

The glycosylphosphatidylinositol (GPI) anchor links over 150 proteins to the cell surface and is present on every cell type. Many of these proteins play crucial roles in neuronal development and function. Mutations in 18 of the 29 genes implicated in the biosynthesis of the GPI anchor have been identified as the cause of GPI biosynthesis deficiencies (GPIBDs) in humans. GPIBDs are associated with intellectual disability and seizures as their cardinal features. An essential component of the GPI transamidase complex is PIGU, along with PIGK, PIGS, PIGT, and GPAA1, all of which link GPI-anchored proteins (GPI-APs) onto the GPI anchor in the endoplasmic reticulum (ER). Here, we report two homozygous missense mutations (c.209T>A [p.Ile70Lys] and c.1149C>A [p.Asn383Lys]) in five individuals from three unrelated families. All individuals presented with global developmental delay, severe-to-profound intellectual disability, muscular hypotonia, seizures, brain anomalies, scoliosis, and mild facial dysmorphism. Using multicolor flow cytometry, we determined a characteristic profile for GPI transamidase deficiency. On granulocytes this profile consisted of reduced cell-surface expression of fluorescein-labeled proaerolysin (FLAER), CD16, and CD24, but not of CD55 and CD59; additionally, B cells showed an increased expression of free GPI anchors determined by T5 antibody. Moreover, computer-assisted facial analysis of different GPIBDs revealed a characteristic facial gestalt shared among individuals with mutations in PIGU and GPAA1. Our findings improve our understanding of the role of the GPI transamidase complex in the development of nervous and skeletal systems and expand the clinical spectrum of disorders belonging to the group of inherited GPI-anchor deficiencies.

Biallelic Mutations in UNC80 Cause Persistent Hypotonia, Encephalopathy, Growth Retardation, and Severe Intellectual Disability.

Ion channel proteins are required for both the establishment of resting membrane potentials and the generation of action potentials. Hundreds of mutations in genes encoding voltage-gated ion channels responsible for action potential generation have been found to cause severe neurological diseases. In contrast, the roles of voltage-independent "leak" channels, important for the establishment and maintenance of resting membrane potentials upon which action potentials are generated, are not well established in human disease. UNC80 is a large component of the NALCN sodium-leak channel complex that regulates the basal excitability of the nervous system. Loss-of-function mutations of NALCN cause infantile hypotonia with psychomotor retardation and characteristic facies (IHPRF). We report four individuals from three unrelated families who have homozygous missense or compound heterozygous truncating mutations in UNC80 and persistent hypotonia, encephalopathy, growth failure, and severe intellectual disability. Compared to control cells, HEK293T cells transfected with an expression plasmid containing the c.5098C>T (p.Pro1700Ser) UNC80 mutation found in one individual showed markedly decreased NALCN channel currents. Our findings demonstrate the fundamental significance of UNC80 and basal ionic conductance to human health.

Treating women of reproductive age with valproate. / Valproatbehandling av fertile kvinner.

The question of valproate use by women of reproductive age is important, complicated and timely. The drug can be extremely harmful to the fetus, but some pregnant women with epilepsy will continue to have seizures if they don't take it.

Frequency of epilepsy and pathological EEG findings in a Norwegian sample of children with fetal alcohol spectrum disorder: Impact on cognition and adaptive functioning.

BACKGROUND: Fetal alcohol spectrum disorder (FASD) comprises a combination of developmental, cognitive, and behavioral disabilities that occur in children exposed to alcohol prenatally. A higher prevalence of epilepsy and pathological electroencephalographic (EEG) features have also been reported in individuals with FASD. We examined the frequency of epilepsy, pathological EEG findings, and their implications for cognitive and adaptive functioning in children with FASD. METHODS: We conducted a cross-sectional study of 148 children with FASD who underwent a multidisciplinary assessment and a 120-min EEG recording. Group comparisons and regression analyses were performed to test the associations between epilepsy and pathological EEG findings, FASD subgroups and neurocognitive test results and adaptive functioning. RESULTS: The frequency of epilepsy was 6%, which compares with 0.7% in Norway overall. Seventeen percent of children without epilepsy had pathological EEG findings. Attention-deficit hyperactivity disorder (ADHD) was diagnosed in 64% of the children. Children with epilepsy and/or pathological EEG findings had comparable cognitive and adaptive scores to those with normal EEG. However, children with frontal EEG pathology (without epilepsy) had significantly lower scores on the IQ indices Processing speed and Working memory than FASD children without such findings, irrespective of ADHD comorbidity. CONCLUSIONS: There was a greater prevalence of epilepsy among children with FASD than in the general Norwegian population. A greater frequency of EEG pathology was also evident in children without epilepsy, across all FASD subgroups. Irrespective of epilepsy, ADHD comorbidity, and FASD subgroup, children with frontal EEG pathology, despite having a normal total IQ, showed significantly slower processing speed and poorer working memory, which may indicate specific executive function deficits that could affect learning and adaptive functioning.

Sleep disturbances in Norwegian children with fetal alcohol spectrum disorders (FASD) with and without a diagnosis of attention-deficit hyperactivity disorder or epilepsy.

BACKGROUND: Fetal alcohol spectrum disorder (FASD) describes a combination of developmental, cognitive, and behavioral disabilities in children with prenatal exposure to alcohol. The literature suggests that there are higher rates of sleep disturbances in these children. Few studies have investigated sleep disturbances in relation to common comorbidities of FASD. We examined the prevalence of disturbed sleep and the relationship between parent-reported sleep problems in different FASD subgroups and comorbidities like epilepsy or attention-deficit hyperactivity disorder (ADHD) and impact on clinical functioning. METHODS: In this prospective cross-sectional survey, caregivers of 53 children with FASD completed the Sleep Disturbance Scale for Children (SDSC). Information about comorbidities was collected, and EEG and assessment of IQ, daily-life executive and adaptive functioning were performed. Group comparisons and ANCOVA interaction models were used to test the associations between different sleep disturbances and clinical factors that could interfere with sleep. RESULTS: An abnormal sleep score on the SDSC was very common, affecting 79% of children (n = 42) with equal prevalence in all FASD subgroups. Difficulty falling asleep was the most common sleep problem, followed by difficulty staying asleep and waking early. The incidence of epilepsy was 9.4%, with an abnormal EEG seen in 24.5%, and a diagnosis of ADHD in 47.2% of children. The distribution of these conditions was equal in all FASD subgroups. Children with signs of sleep disturbance had poorer working memory, executive function, and adaptive functioning. Children with ADHD had a greater prevalence of sleep disturbance than those without ADHD (OR 1.36; 95% CI 1.03 to 1.79). CONCLUSION: Problems with sleep are very common in FASD children and seem independent of FASD subgroup and the presence of epilepsy or a pathological EEG finding, while those with ADHD had more sleep problems. The study underscores the importance of screening for sleep disturbances in all children with FASD as these problems may be treatable.

The spectrum of pyridoxine dependent epilepsy across the age span: A nationwide retrospective observational study.

BACKGROUND: Pyridoxine-dependent epilepsy (PDE) is a rare seizure disorder usually presenting with neonatal seizures. Most cases are caused by biallelic pathogenic ALDH7A1variants. While anti-seizure medications are ineffective, pyridoxine provides seizure control, and dietary interventions may be of benefit. As the natural history beyond adolescence is insufficiently explored, our study aimed to assess the spectrum of PDE at various ages in Norway. METHODS: Patients were ascertained by contacting all Norwegian paediatric, neurological, and neurohabilitation departments and relevant professional societies. Medical records were collected and reviewed. RESULTS: We identified 15 patients treated for PDE; 13 had ALDH7A1 variants (PDE-ALDH7A1), one had PNPO deficiency, and in one, aetiology remained obscure. Of those with PDE-ALDH7A1, 12 were alive at time of study; five were > 18 years old and six were < 4 years. Median age was 10 years (range 2 months-53 years). Estimated minimum prevalence was 6.3/million among children and 1.2/million among adults. Ten had seizure onset on the first day of life. Perinatal complications and neuroradiological abnormalities suggested additional seizure aetiologies in several patients. Pyridoxine had immediate effect in six, while six had delayed (>1 h) or uncertain effect. Median delay from first seizure to continuous treatment was 11 days (range 0-42). Nine experienced breakthrough seizures with intercurrent disease or due to pyridoxine discontinuation. Cognitive outcomes ranged from normal to severe intellectual disability. The condition appeared to remain stable in adult life. SIGNIFICANCE: We found a much higher prevalence of PDE-ALDH7A1 in children relative to adults, suggesting previous underdiagnosis and early mortality. Perinatal complications are common and can delay diagnosis and initiation of pyridoxine treatment. Lifelong and continuous treatment with pyridoxine is imperative. Due to better diagnostics and survival, the number of adult patients is expected to rise.

Alternative polyadenylation alters protein dosage by switching between intronic and 3'UTR sites.

Alternative polyadenylation (APA) creates distinct transcripts from the same gene by cleaving the pre-mRNA at poly(A) sites that can lie within the 3' untranslated region (3'UTR), introns, or exons. Most studies focus on APA within the 3'UTR; however, here, we show that CPSF6 insufficiency alters protein levels and causes a developmental syndrome by deregulating APA throughout the transcript. In neonatal humans and zebrafish larvae, CPSF6 insufficiency shifts poly(A) site usage between the 3'UTR and internal sites in a pathway-specific manner. Genes associated with neuronal function undergo mostly intronic APA, reducing their expression, while genes associated with heart and skeletal function mostly undergo 3'UTR APA and are up-regulated. This suggests that, under healthy conditions, cells toggle between internal and 3'UTR APA to modulate protein expression.

A Survey on Cannabinoid Treatment of Pediatric Epilepsy Among Neuropediatricians in Scandinavia and Germany.

Objectives: There is an increasing interest in cannabinoid-based products for the treatment of refractory pediatric epilepsy. However, a licensed cannabidiol (CBD) product was first approved for use by the European regulatory authorities in 2019. We aimed to obtain knowledge about clinical experience and attitudes toward cannabinoid use for epilepsy treatment among neuropediatricians in Scandinavia and Germany in the era before a CBD-product was commercially licensed and available. Study design: An internet-based questionnaire (Survey Monkey) was distributed by email to members of neuropediatric societies in Sweden, Germany, Denmark, and Norway between February and April 2018. One reminder email was sent. Results: Eighty-six responded. Only 10 of 86 (12%) respondents had personal experience with off-label prescription of cannabinoid-based products, mainly for severe refractory pediatric epilepsies like Dravet syndrome and Lennox-Gastaut syndrome. However, 49 respondents (57%) had been exposed to relatives of patients that had requested or wanted to discuss cannabinoid therapy, and 32 (37%) respondents knew about cannabinoid self-medication. The knowledge regarding cannabinoid-based therapy among the respondents was overall limited. Main reasons for not prescribing cannabinoid-based therapy were concerns about law regulations and lack of an available product. Conclusion: Off-label cannabinoid-based therapy for pediatric epilepsy was not widely prescribed by neuropediatricians in Scandinavia and Germany in 2018.

Autonomic nervous system function in infants and adolescents: impact of autonomic tests on heart rate variability.

Measurement of heart rate variability (HRV) shows information on the functional state of the autonomic nervous system (ANS). In adults there are standardized autonomic tests and well-established ranges of normal values, which is not the case in children. The aim of the present study was (1) to introduce an ANS test battery, especially for children and adolescents; (2) to establish normative HRV parameters; and (3) to determine the impact of ANS tests on HRV parameters compared with baseline measurements. We investigated 100 healthy children and adolescents between 6 and 15 years old. We subdivided the investigated group into a group of children (5-11 years old) and adolescents (12-15 years old) and measured HRV by time and frequency domain parameters during baseline, rhythmic breathing, Valsalva test, active standing, tilt-table testing, and handgrip test. The normative HRV data are presented by means, SDs, medians, and percentiles. The results described refer to baseline values for each HRV parameter separately to demonstrate the influence of age on HRV parameters. The study results present not only first normative HRV data for an autonomic test battery especially adapted to children and adolescents, but they also quantify the autonomic changes induced by test procedures compared with baseline measurements.

High incidence of vaproate-induced coagulation disorders in children receiving valproic acid: a prospective study.

Reports have been published on blood coagulation disturbances by valproate therapy. In the present prospective trial, blood samples were drawn before valproate therapy, after 6 weeks of therapy, after more than 6 weeks and after longer than 6 months of valproate therapy from 23 children newly treated with valproate. Two children developed thrombocytopenia, and six children with initial normal von Willebrand factor showed acquired von Willebrand's disease. Fibrinogen levels dropped below the lower limit in 12 patients and subnormal factor XIII plasma levels were observed in 17% of patients. No patient developed signs of hemorrhage. Eight percent of patients developed valproate-induced thrombocytopenia. Reduction in platelets did not reach statistic significance. Thrombelastography showed a 47% incidence of altered platelet function. We found a statistically significant, positive correlation between clotting time of collagen extrinsic pathway inhibitor and, accordingly, adenosindiphosphate and valproate level. Plasmatic coagulation investigations showed a significant decrease of prothrombin time. Activated partial thromboplastin time measurements also showed significant prolongation with valproate. Activity of von Willebrand factor antigen and von Willebrand factor ristocetin cofactor significantly decreased. Factor XIII activity significantly decreased after valproate therapy for longer than 6 months (17% of children). Fibrinogen was significantly reduced. In the coagulatory system a decrease in the main antiprotease antithrombin III activity was observed. Blood coagulation disturbances are common in patients with valproate, but rarely become clinically symptomatic. Acquired von Willebrand's disease and hypofibrinogenemia may become relevant in patients with surgery or trauma. Particular attention should be paid to factor-XIII deficiency, which is especially seen with valproate therapy.

Vagus nerve stimulation improves severely impaired heart rate variability in a patient with Lennox-Gastaut-Syndrome.

Vagus nerve stimulation (VNS) is a new therapeutic option for refractory epilepsy. We report a patient with Lennox-Gastaut-Syndrome (LGS) and a severe impairment of heart rate variability (HRV), we could demonstrate in our patient that HRV was improved by VNS.

Valproic acid-induced pancreatitis: 16 new cases and a review of the literature.

BACKGROUND: Acute pancreatitis is rarely seen in children, and, in contrast to cases in adults, it is often drug induced. One possible medication is the antiepileptic drug valproic acid (VPA), which is commonly prescribed for generalized and focal epilepsy, migraine, neuropathic pain, and bipolar disorder. The common side effects associated with VPA are typically benign, but less common but more serious adverse effects may occur. These include hepatotoxicity, hyperammonemic encephalopathy, coagulation disorders, and pancreatitis. Since 1979, a few cases of pancreatitis induced by VPA have been published in the medical literature. METHODS: We mailed a questionnaire to all members of the "German Section of the International League against Epilepsy," asking about VPA-induced side effects. We also reviewed the medical literature for VPA-induced pancreatitis. RESULTS: Fifty-three publications (90 patients) published from 1979 to 2005 were found. Our survey in Germany, however, yielded 16 cases of pancreatitis from 1994 to 2003 whose original files we could study in detail. None of these patients had been published previously. CONCLUSIONS: The difference between 90 patients reported worldwide from 1979 to 2005 and the 16 new documented cases from only Germany over 10 years corroborates that the occurrence of this severe side effect is under reported.

Reversible hepatotoxicity, pancreatitis, coagulation disorder and simultaneous bone marrow suppression with valproate in a 2-year-old girl.

Valproic acid (VPA) is considered to be a drug of first choice for the therapy of generalized and focal epilepsies, including special epileptic syndromes like the WEST-syndrome. The drug is usually well tolerated; rare serious complications may occur in some patients, including haemorrhagic pancreatitis, coagulapathies, bone marrow suppression, VPA-induced hepatotoxicity and encephalopathy. We report a case of combined appearance of several severe VPA-associated side effects in a two- and a half-year-old girl with lissencephaly.

Internet-based knowledge management database for children and adults with epilepsy: a possible model project for evidence-based medicine in the future.

With an incidence of nearly 1%, epilepsy represents one of the most frequent diseases in the population. Nevertheless substantial information gaps exist as to the exact incidence, prevalence, therapy and particularly to associated therapeutic success. Adequate studies are not performed on many of these issues which are primarily beyond the current interests of the pharmaceutical industry. An Internet-based knowledge management database is presented to illustrate initial results of the online system with a focus on medication and side effects (http://www.ligaepilepsie.org/KnowledgeDB/index.htm). Further, it is worth noting that this database was designed as a potential model for similar projects in other medical fields.