A novel somatic mutation in GNB2 provides new insights to the pathogenesis of Sturge-Weber syndrome.

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder characterized by vascular malformations affecting skin, eyes and leptomeninges of the brain, which can lead to glaucoma, seizures and intellectual disability. The discovery of a disease-causing somatic missense mutation in the GNAQ gene, encoding an alpha chain of heterotrimeric G-proteins, has initiated efforts to understand how G-proteins contribute to SWS pathogenesis. The mutation is predominantly detected in endothelial cells and is currently believed to affect downstream MAPK signalling. In this study of six Norwegian patients with classical SWS, we aimed to identify somatic mutations through deep sequencing of DNA from skin biopsies. Surprisingly, one patient was negative for the GNAQ mutation, but instead harbored a somatic mutation in GNB2 (NM_005273.3:c.232A>G, p.Lys78Glu), which encodes a beta chain of the same G-protein complex. The positions of the mutant amino acids in the G-protein are essential for complex reassembly. Therefore, failure of reassembly and continuous signalling is a likely consequence of both mutations. Ectopic expression of mutant proteins in endothelial cells revealed that expression of either mutant reduced cellular proliferation, yet regulated MAPK signalling differently, suggesting that dysregulated MAPK signalling cannot fully explain the SWS phenotype. Instead, both mutants reduced synthesis of Yes-associated protein (YAP), a transcriptional co-activator of the Hippo signalling pathway, suggesting a key role for this pathway in the vascular pathogenesis of SWS. The discovery of the GNB2 mutation sheds novel light on the pathogenesis of SWS and suggests that future research on targets of treatment should be directed towards the YAP, rather than the MAPK, signalling pathway.

Health-related quality of life in adults with drug-resistant focal epilepsy treated with modified Atkins diet in a randomized clinical trial.

Ketogenic diet, a high-fat, low-carbohydrate diet, is an established treatment for patients with severe epilepsy. We have previously reported a moderate reduction in seizure frequency after treatment with a modified Atkins diet. This study aimed to see whether dietary therapy impacts patients' health-related quality of life (HRQOL). In a randomized controlled design, we compared the change in self-reported HRQOL among adults with difficult-to-treat epilepsy after a 12-week diet intervention. Thirty-nine patients with drug-resistant focal epilepsy (age = 16-65 years) were randomized to eat a modified Atkins diet with maximum 16 g of carbohydrate per day (diet group, n = 19) or to continue eating habitual diet (control group, n = 20). No changes to the other epilepsy treatments were allowed. Patient-reported HRQOL was assessed with the Quality of Life in Epilepsy Inventory-89 (QOLIE-89). The diet group experienced a statistically significant improvement in mean total score of QOLIE-89 of 10 points compared to controls (p = .002). Moreover, although not statistically significant when using a cutoff of 50% seizure reduction, our data suggest an association between diet-induced reduction in seizure frequency and improvement in HRQOL. The improvement in HRQOL was not associated with diet-induced weight reduction.

Gain-of-function variants in GABRD reveal a novel pathway for neurodevelopmental disorders and epilepsy.

A potential link between GABRD encoding the δ subunit of extrasynaptic GABAA receptors and neurodevelopmental disorders has largely been disregarded due to conflicting conclusions from early studies. However, we identified seven heterozygous missense GABRD variants in 10 patients with neurodevelopmental disorders and generalized epilepsy. One variant occurred in two sibs of healthy parents with presumed somatic mosaicism, another segregated with the disease in three affected family members, and the remaining five occurred de novo in sporadic patients. Electrophysiological measurements were used to determine the functional consequence of the seven missense δ subunit variants in receptor combinations of α1ß3δ and α4ß2δ GABAA receptors. This was accompanied by analysis of electroclinical phenotypes of the affected individuals. We determined that five of the seven variants caused altered function of the resulting α1ß3δ and α4ß2δ GABAA receptors. Surprisingly, four of the five variants led to gain-of-function effects, whereas one led to a loss-of-function effect. The stark differences between the gain-of-function and loss-of function effects were mirrored by the clinical phenotypes. Six patients with gain-of-function variants shared common phenotypes: neurodevelopmental disorders with behavioural issues, various degrees of intellectual disability, generalized epilepsy with atypical absences and generalized myoclonic and/or bilateral tonic-clonic seizures. The EEG showed qualitative analogies among the different gain-of-function variant carriers consisting of focal slowing in the occipital regions often preceding irregular generalized epileptiform discharges, with frontal predominance. In contrast, the one patient carrying a loss-of-function variant had normal intelligence and no seizure history, but has a diagnosis of autism spectrum disorder and suffers from elevated internalizing psychiatric symptoms. We hypothesize that increase in tonic GABA-evoked current levels mediated by δ-containing extrasynaptic GABAA receptors lead to abnormal neurotransmission, which represent a novel mechanism for severe neurodevelopmental disorders. In support of this, the electroclinical findings for the gain-of-function GABRD variants resemble the phenotypic spectrum reported in patients with missense SLC6A1 (GABA uptake transporter) variants. This also indicates that the phenomenon of extrasynaptic receptor overactivity is observed in a broader range of patients with neurodevelopmental disorders, because SLC6A1 loss-of-function variants also lead to overactive extrasynaptic δ-containing GABAA receptors. These findings have implications when selecting potential treatment options, as a substantial portion of available antiseizure medication act by enhancing GABAergic function either directly or indirectly, which could exacerbate symptoms in patients with gain-of-function GABRD variants.

Genome-wide decrease in DNA methylation in adults with epilepsy treated with modified ketogenic diet: A prospective study.

OBJECTIVE: The aim of this study was to investigate the impact of the modified ketogenic diet on DNA methylation in adults with epilepsy. METHODS: In this prospective study, we investigated the genome-wide DNA methylation in whole blood in 58 adults with epilepsy treated with the modified ketogenic for 12 weeks. Patients were recruited from the National Center for Epilepsy, Norway, from March 1, 2011 to February 28, 2017. DNA methylation was analyzed using the Illumina Infinium MethylationEPIC BeadChip array. Analysis of variance and paired t-test were used to identify differentially methylated loci after 4 and 12 weeks of dietary treatment. A false discovery rate approach with a significance threshold of <5% was used to adjust for multiple comparisons. RESULTS: We observed a genome-wide decrease in DNA methylation, both globally and at specific sites, after 4 and 12 weeks of dietary treatment. A substantial share of the differentially methylated positions (CpGs) were annotated to genes associated with epilepsy (n = 7), lipid metabolism (n = 8), and transcriptional regulation (n = 10). Furthermore, five of the identified genes were related to inositol phosphate metabolism, which may represent a possible mechanism by which the ketogenic diet attenuates seizures. SIGNIFICANCE: A better understanding of the modified ketogenic diet's influence at the molecular level may be the key to unraveling the mechanisms by which the diet can ameliorate seizures and possibly to identifying novel therapeutic targets for epilepsy.

Substantial early changes in bone and calcium metabolism among adult pharmacoresistant epilepsy patients on a modified Atkins diet.

OBJECTIVE: The aim of this study was to investigate whether the modified Atkins diet (MAD), a variant of the ketogenic diet, has an impact on bone- and calcium (Ca) metabolism. METHODS: Two groups of adult patients with pharmacoresistant epilepsy were investigated. One, the diet group (n = 53), was treated with MAD for 12 weeks, whereas the other, the reference group (n = 28), stayed on their habitual diet in the same period. All measurements were performed before and after the 12 weeks in both groups. We assessed bone health by measuring parathyroid hormone (PTH), Ca, 25-OH vitamin D (25-OH vit D), 1,25-OH vitamin D (1,25-OH vit D), phosphate, alkaline phosphatase (ALP), and the bone turnover markers procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide collagen type 1 (CTX-1). In addition, we examined the changes of sex hormones (estradiol, testosterone, luteinizing hormone, follicle-stimulating hormone), sex hormone-binding globulin, and leptin. RESULTS: After 12 weeks of MAD, we found a significant reduction in PTH, Ca, CTX-1, P1NP, 1,25-OH vit D, and leptin. There was a significant increase in 25-OH vit D. These changes were most pronounced among patients <37 years old, and in those patients with the highest body mass index (≥25.8 kg/m²), whereas sex and type of antiseizure medication had no impact on the results. For the reference group, the changes were nonsignificant for all the analyses. In addition, the changes in sex hormones were nonsignificant. SIGNIFICANCE: Twelve weeks of MAD treatment leads to significant changes in bone and Ca metabolism, with a possible negative effect on bone health as a result. A reduced level of leptin may be a triggering mechanism. The changes could be important for patients on MAD, and especially relevant for those patients who receive treatment with MAD at an early age before peak bone mass is reached.

Phenotypic spectrum and transcriptomic profile associated with germline variants in TRAF7.

PURPOSE: Somatic variants in tumor necrosis factor receptor-associated factor 7 (TRAF7) cause meningioma, while germline variants have recently been identified in seven patients with developmental delay and cardiac, facial, and digital anomalies. We aimed to define the clinical and mutational spectrum associated with TRAF7 germline variants in a large series of patients, and to determine the molecular effects of the variants through transcriptomic analysis of patient fibroblasts. METHODS: We performed exome, targeted capture, and Sanger sequencing of patients with undiagnosed developmental disorders, in multiple independent diagnostic or research centers. Phenotypic and mutational comparisons were facilitated through data exchange platforms. Whole-transcriptome sequencing was performed on RNA from patient- and control-derived fibroblasts. RESULTS: We identified heterozygous missense variants in TRAF7 as the cause of a developmental delay-malformation syndrome in 45 patients. Major features include a recognizable facial gestalt (characterized in particular by blepharophimosis), short neck, pectus carinatum, digital deviations, and patent ductus arteriosus. Almost all variants occur in the WD40 repeats and most are recurrent. Several differentially expressed genes were identified in patient fibroblasts. CONCLUSION: We provide the first large-scale analysis of the clinical and mutational spectrum associated with the TRAF7 developmental syndrome, and we shed light on its molecular etiology through transcriptome studies.

Trait impulsivity correlates with active myoclonic seizures in genetic generalized epilepsy.

BACKGROUND: Juvenile myoclonic epilepsy (JME) is a common subtype of genetic generalized epilepsy (GGE) arising in adolescence and is often associated with executive function (EF) deficits. Some EF components like response inhibition have been extensively evaluated in JME, but few studies have focused upon trait impulsivity or compared between GGE subtypes. The aim of the present study was to compare the association of trait impulsivity in JME with other GGE subtypes. METHODS: Patients with GGE aged between 14 and 40 years (n = 137) were divided into those with JME (n = 92) and those with other GGEs (n = 45: 8 childhood absence epilepsy (CAE), 22 juvenile absence epilepsy (JAE), and 15 epilepsy with generalized tonic-clonic seizures only (EGTCS)). The study participants were recruited through medical records of the general population of Buskerud County and the neighboring municipalities, covering 477,000 people or 9.1% of Norway's total population. All participants underwent a clinical interview including the Barratt Impulsiveness Scale (BIS), an established measure of trait impulsivity. We controlled for other potential predictors of BIS score using analysis of covariance (ANCOVA). RESULTS: There were no differences between JME and other types of GGE for BIS scores, but the presence of myoclonic seizures within the last year, irrespective of GGE subtype, was independently associated with significantly increased behavioral impulsivity. CONCLUSIONS: This study demonstrates that trait impulsivity in GGE is most strongly related to the recent occurrence of myoclonic seizures rather than GGE subtype.

Effects of modified Atkins diet on thyroid function in adult patients with pharmacoresistant epilepsy.

INTRODUCTION: The use of ketogenic diet as a supplement to antiseizure medication (ASM) in refractory epilepsy has increased the past decades. This high-fat, low-carbohydrate diet mimics the metabolic state of fasting and is generally well-tolerated. However, the long-term adverse effects of the diet are unclear. The purpose of this study was to investigate whether the modified Atkins diet (MAD), a variant of the ketogenic diet, may have an impact on thyroid hormone levels. METHODS: We assessed thyroid function by measuring thyroid stimulation hormone (TSH), fT4, T3, fT3, and rT3 before diet start (baseline) and after 12 weeks on the diet in 53 adult patients with drug-resistant epilepsy. Further, we examined the correlation between the changes in thyroid function during dietary treatment and type of (i) change in seizure frequency, (ii) drugs in use, and (iii) degree of ketosis. RESULTS: After 12 weeks on the diet, we found a significant reduction in T3 and fT3 values (13.4% and 10.6%, respectively) and a significant increase in fT4 values (12.1%) compared with baseline. In addition, there was an insignificant increase in TSH and rT3. These changes were similar in women and men, and there was no correlation to drugs in use (enzyme-inducing vs. nonenzyme-inducing drugs), changes in seizure frequency, or level of ketosis. CONCLUSION: This study indicates that dietary treatment for epilepsy may bring about a modest fall in thyroid hormone levels. This could be relevant for those patients with low thyroid hormones and those treated with ASMs known to lower thyroid hormone levels. A cumulative effect of ASMs, low basal thyroid hormone levels, and ketogenic diet may therefore be of clinical importance in the case of thyroid hormones when treating patients with MAD.

The effect of infliximab in patients with chronic low back pain and Modic changes (the BackToBasic study): study protocol of a randomized, double blind, placebo-controlled, multicenter trial.

BACKGROUND: Low back pain is common and a significant number of patients experience chronic low back pain. Current treatment options offer small to moderate effects. Patients with vertebral bone marrow lesions visualized as Modic changes on magnetic resonance imaging may represent a subgroup within the low back pain population. There is evidence for inflammatory mediators being involved in development of Modic changes; hence, suppression of inflammation could be a treatment strategy for these patients. This study examines the effect of anti-inflammatory treatment with the TNF-α inhibitor infliximab in patients with chronic low back pain and Modic changes. METHODS/DESIGN: The BackToBasic trial is a multicenter, double blind, randomized controlled trial conducted at six hospitals in Norway, comparing intravenous infusions with infliximab with placebo. One hundred twenty-six patients aged 18-65 with chronic low back pain and type 1 Modic changes will be recruited from secondary care outpatients' clinics. The primary outcome is back pain-specific disability at day 154 (5 months). The study is designed to detect a difference in change of 10 (SD 18) in the Oswestry Disability Index at day 154/ 5 months. The study also aims to refine MRI-assessment, investigate safety and cost-effectiveness and explore the underlying biological mechanisms of Modic changes. DISCUSSION: Finding treatments that target underlying mechanisms could pose new treatment options for patients with low back pain. Suppression of inflammation could be a treatment strategy for patients with low back pain and Modic changes. This paper presents the design of the BackToBasic study, where we will assess the effect of an anti-inflammatory treatment versus placebo in patients with chronic low back pain and type 1 Modic changes. The study is registered at ClinicalTrials.gov under the identifier NCT03704363 . The EudraCT Number: 2017-004861-29.

Novel UCHL1 mutations reveal new insights into ubiquitin processing.

Recessive loss of function of the neuronal ubiquitin hydrolase UCHL1 has been implicated in early-onset progressive neurodegeneration (MIM no. 615491), so far only in one family. In this study a second family is characterized, and the functional consequences of the identified mutations in UCHL1 are explored. Three siblings developed childhood-onset optic atrophy, followed by spasticity and ataxia. Whole exome sequencing identified compound heterozygous variants in UCHL1, c.533G > A (p.Arg178Gln) and c.647C > A (p.Ala216Asp), cosegregating with the phenotype. Enzymatic activity of purified recombinant proteins analysed by ubiquitin hydrolase assays showed a 4-fold increased hydrolytic activity of the recombinant UCHL1 mutant Arg178Gln compared to wild type, whereas the Ala216Asp protein was insoluble. Structural 3D analysis of UCHL1 by computer modelling suggests that Arg178 is a rate-controlling residue in catalysis which is partly abolished in the Arg178Gln mutant and, consequently, the Arg178Gln mutant increases the enzymatic turnover. UCHL1 protein levels in fibroblasts measured by targeted mass spectrometry showed a total amount of UCHL1 in control fibroblasts about 4-fold higher than in the patients. Hence, studies of the identified missense variants reveal surprisingly different functional consequences as the insoluble Ala216Asp variant leads to loss of function, whereas the Arg178Gln leads to increased enzyme activity. The reported patients have remarkably preserved cognition, and we propose that the increased enzyme activity of the Arg178Gln variant offers a protective effect on cognitive function. This study establishes the importance of UCHL1 in neurodegeneration, provides new mechanistic insight about ubiquitin processing, and underlines the complexity of the different roles of UCHL1.

Pharmacokinetic interaction between modified Atkins diet and antiepileptic drugs in adults with drug-resistant epilepsy.

OBJECTIVE: The aim was to examine the influence of modified Atkins diet on serum concentration of antiepileptic drugs (AEDs). METHODS: Prospective data from 63 adult patients with either focal or generalized drug-resistant epilepsy recruited to 12-week dietary treatment as add-on to AEDs are analyzed. AED serum concentrations, ketones, glucose, and hemoglobin A1c were measured before and after the dietary intervention. Paired t test was used and Spearman correlation coefficient, r, was estimated. RESULTS: Mean age was 37 years (range 16-65 years). Mean serum concentrations of carbamazepine, clobazam, and valproate were significantly reduced after 4 and 12 weeks of the diet period (<.001 ≤ P ≤ .02). Levels of lacosamide, lamotrigine, and topiramate were less reduced (.02 ≤ P ≤ .08), whereas the serum concentrations of oxcarbazepine, zonisamide, and levetiracetam were unchanged (.06 ≤ P ≤ .90). The largest reduction in serum concentration was found for clobazam: mean reduction after 12 weeks was 1.5 µmol/L (34%). Percent change in serum concentration after 4 and 12 weeks of all drugs analyzed was -10.5% (95% confidence interval [CI] -14.1 to -6.8; n = 60; P < .001) and -13.5% (95% CI -18.8 to -8.3; n = 56; P < .001), respectively. Percent change in serum concentration of AEDs was not significantly correlated to percent change in seizure frequency after 12 weeks of dietary treatment (r = .14, P = .33, n = 53) but negatively correlated to urine ketosis (r = -.43; P = .003; n = 46). SIGNIFICANCE: A reduction in AED serum concentrations may counteract a seizure-reducing effect of the diet, and in patients without such an effect, it may cause seizure aggravation. Thus, we recommend that clinicians who are treating patients with ketogenic diets monitor serum concentrations of the concomitant AEDs.

Psychosocial complications in juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) constitutes about 10% of all epilepsies. Because of executive dysfunction, people with JME may be prone to impulsivity and risk-taking behavior. Our aim was to investigate whether psychosocial issues associated with impulsivity are more prominent in people with JME than in those with other types of genetic generalized epilepsy (GGE). Patients with GGE were recruited retrospectively through the Drammen Hospital records in Buskerud County, Norway, 1999-2013. They were invited to a semi-structured interview, either at the hospital or at home. Ninety-two patients with JME and 45 with other types of GGE were interviewed. Variables were evaluated in terms of their association with JME versus other GGE diagnosis using a logistic regression model. Juvenile myoclonic epilepsy was associated with use of illicit recreational drugs and police charges, although with borderline significance (odds ratio [OR] 3.4, p = 0.087 and OR 4.2, p = 0.095); JME was also associated with being examined for attention-deficit hyperactivity disorder (ADHD) in females (OR 15.5, p = 0.015), a biological parent with challenges like addiction or violent behavior (OR 3.5, p = 0.032), and use of levetiracetam (OR 5.1, p = 0.014). After controlling for group differences, we found psychosocial complications to be associated with JME, potentially influencing the lives of the individuals and their families to a greater extent than the seizures per se. Thus, JME should be considered a disorder of the brain in a broader sense than a condition with seizures only.

Pyruvate dehydrogenase deficiency. / Pyruvatdehydrogenase-mangel.

Pyruvate dehydrogenase deficiency is a rare mitochondrial disease leading to energy deficiency in the cells. This particularly affects the central nervous system, resulting in a broad range of neurological symptoms.

Effect of modified Atkins diet in adults with drug-resistant focal epilepsy: A randomized clinical trial.

OBJECTIVE: Ketogenic diets reduce seizures in children with drug-resistant epilepsy. Whether adults benefit from similar treatment has not been clarified. We therefore examined the efficacy of the modified Atkins diet in adults with drug-resistant focal epilepsy. METHODS: We performed a randomized clinical trial (RCT) with patients >16 years who had at least 3 seizures per month despite having tried at least 3 antiepileptic drugs. They were randomized to either 12 weeks on the modified Atkins diet (diet group) or habitual diet (control group). Primary endpoint was a change in seizure frequency from baseline to the intervention period, comparing those on diet with controls. RESULTS: We assigned 37 patients to the diet group and 38 to the control group. Nine of the patients in the diet group and 4 controls were excluded. Of those who completed the dietary intervention (n = 24), median seizure change was -1.0 (interquartile range [IQR] -13.7-8.8), while in the control group (n = 32) the median change was 4.5 (IQR -4.8-33.5). The median difference between the groups was -7.0 (95% confidence interval [CI] -37.0-3.0; P = .21). In the intention-to-treat analysis, the relative risk (RR) for achieving >50% seizure reduction was 1.8 (95% CI 0.3-10.2; P = .65), while for achieving >25% seizure reduction RR was 2.43 (95% CI 0.94-6.28; P = .06). We observed no serious adverse events. SIGNIFICANCE: In this RCT investigating the effect of an adjunctive modified Atkins diet on seizure frequency in adults with difficult-to-treat focal epilepsy, we found a significant reduction in seizure frequency in the diet group compared to the controls, but only for moderate benefit (>25% seizure reduction) among those who completed the intervention. However, seizure response varied considerably between individuals, perhaps negatively influenced by a drop in serum concentrations of antiepileptic drugs.

FILTUS: a desktop GUI for fast and efficient detection of disease-causing variants, including a novel autozygosity detector.

UNLABELLED: FILTUS is a stand-alone tool for working with annotated variant files, e.g. when searching for variants causing Mendelian disease. Very flexible in terms of input file formats, FILTUS offers efficient filtering and a range of downstream utilities, including statistical analysis of gene sharing patterns, detection of de novo mutations in trios, quality control plots and autozygosity mapping. The autozygosity mapping is based on a hidden Markov model and enables accurate detection of autozygous regions directly from exome-scale variant files. AVAILABILITY AND IMPLEMENTATION: FILTUS is written in Python and runs on Windows, Mac and Linux. Binaries and source code are freely available at http://folk.uio.no/magnusv/filtus.html and on GitHub: https://github.com/magnusdv/filtus Automatic installation is available via PyPI (e.g. pip install filtus). CONTACT: magnusdv@medisin.uio.no SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Biochemical and genetic characterization of an unusual mild PEX3-related Zellweger spectrum disorder.

Patients with PEX3 mutations usually present with a severe form of Zellweger spectrum disorder with death in the first year of life. Whole exome sequencing in adult siblings with intellectual disability revealed a homozygous variant in PEX3 that abolishes the normal splice site. A cryptic acceptor splice site is activated and an in-frame transcript with a deletion is produced. This transcript translates into a protein with residual activity explaining the relatively mild peroxisomal abnormalities and clinical phenotype.

Prevalence of juvenile myoclonic epilepsy in people <30 years of age-A population-based study in Norway.

OBJECTIVE: Despite juvenile myoclonic epilepsy (JME) being considered one of the most common epilepsies, population-based prevalence studies of JME are lacking. Our aim was to estimate the prevalence of JME in a Norwegian county, using updated diagnostic criteria. METHODS: This was a cross-sectional study, based on reviews of the medical records of all patients with a diagnosis of epilepsy at Drammen Hospital in the period 1999-2013. The study population consisted of 98,152 people <30 years of age. Subjects diagnosed with JME, unspecified genetic generalized epilepsy, or absence epilepsy were identified. All of these patients were contacted and asked specifically about myoclonic jerks. Electroencephalography (EEG) recordings and medical records were reevaluated for those who confirmed myoclonic jerks. Information about seizure onset was obtained from the medical records, and annual frequency of new cases was estimated. RESULTS: A total of 55 subjects fulfilled the diagnostic criteria for JME. The point prevalence was estimated at 5.6/10,000. JME constituted 9.3% of all epilepsies in the age group we investigated. Of subjects diagnosed with either unspecified genetic generalized epilepsy or absence epilepsy, 21% and 12%, respectively, had JME. We identified 21 subjects with JME (38%) who had not been diagnosed previously. Six subjects (11%) had childhood absence epilepsy evolving into JME. Between 2009 and 2013, the average frequency of JME per 100,000 people of all ages per year was estimated at 1.7. SIGNIFICANCE: A substantial portion of people with JME seem to go undiagnosed, as was the case for more than one third of the subjects in this study. By investigating subjects diagnosed with unspecified genetic generalized epilepsy or absence epilepsy, we found a prevalence of JME that was considerably higher than previously reported. We conclude that JME may go undiagnosed due to the underrecognition of myoclonic jerks. To make a correct diagnosis, clinicians need to ask specifically about myoclonic jerks.

Pathogenic variants in KCTD7 perturb neuronal K+ fluxes and glutamine transport.

Progressive myoclonus epilepsy is a heterogeneous group of disorders characterized by myoclonic and tonic-clonic seizures, ataxia and cognitive decline. We here present two affected brothers. At 9 months of age the elder brother developed ataxia and myoclonic jerks. In his second year he lost the ability to walk and talk, and he developed drug-resistant progressive myoclonus epilepsy. The cerebrospinal fluid level of glutamate was decreased while glutamine was increased. His younger brother manifested similar symptoms from 6 months of age. By exome sequencing of the proband we identified a novel homozygous frameshift variant in the potassium channel tetramerization domain 7 (KCTD7) gene (NM_153033.1:c.696delT: p.F232fs), which results in a truncated protein. The identified F232fs variant is inherited in an autosomal recessive manner, and the healthy consanguineous parents carry the variant in a heterozygous state. Bioinformatic analyses and structure modelling showed that KCTD7 is a highly conserved protein, structurally similar to KCTD5 and several voltage-gated potassium channels, and that it may form homo- or heteromultimers. By heterologous expression in Xenopus laevis oocytes, we demonstrate that wild-type KCTD7 hyperpolarizes cells in a K+ dependent manner and regulates activity of the neuronal glutamine transporter SAT2 (Slc38a2), while the F232fs variant impairs K+ fluxes and obliterates SAT2-dependent glutamine transport. Characterization of four additional disease-causing variants (R94W, R184C, N273I, Y276C) bolster these results and reveal the molecular mechanisms involved in the pathophysiology of KCTD7-related progressive myoclonus epilepsy. Thus, our data demonstrate that KCTD7 has an impact on K+ fluxes, neurotransmitter synthesis and neuronal function, and that malfunction of the encoded protein may lead to progressive myoclonus epilepsy.

GLUT1-deficiency syndrome: Report of a four-generation Norwegian family with a mild phenotype.

INTRODUCTION: Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is a rare metabolic encephalopathy with a wide variation of clinical phenotypes. Familial variants are often milder than de novo cases, and may therefore remain undiagnosed. The aim of this study was to characterize the clinical course of GLUT1-DS in a four-generation Norwegian family where the oldest generations had never received any treatment. METHOD: Through interviews and clinical investigations, we characterized a family of 26 members, where 11 members had symptoms strongly suggesting GLUT1-DS. All members were offered genetic testing of the SLC2A1 gene. Affected members were offered treatment with ketogenic diet, and the effect of the treatment was registered. RESULTS: We sequenced the SLC2A1 gene in 13 members, and found that 10, all with symptoms, had the c.823G>A (p.Ala275Thr) variant. All affected members had experienced early-onset epilepsy, paroxysmal exercise-induced dyskinesias, and most had mild learning disability. Moreover, some had symptoms and signs of a distal neuropathy in addition to reduced sense of orientation and excessive daytime sleep. Their load of symptoms had decreased over the years, although that they never had received any treatment. Nevertheless, those who started dietary treatment all experienced an improved quality of life. CONCLUSION: We report a four-generation family with GLUT1-DS where the disease has a mild course, even when untreated. In addition to classical GLUT1-DS features, we also describe symptoms which have never been reported in GLUT1-DS previously. As such, this family extends the phenotypic spectrum of GLUT1-DS and underlines the importance of diagnosing also relatively mildly affected patients, even in adult life, as they also seem to benefit from dietary treatment.

Strømme Syndrome Is a Ciliary Disorder Caused by Mutations in CENPF.

Strømme syndrome was first described by Strømme et al. (1993) in siblings presenting with "apple peel" type intestinal atresia, ocular anomalies and microcephaly. The etiology remains unknown to date. We describe the long-term clinical follow-up data for the original pair of siblings as well as two previously unreported siblings with a severe phenotype overlapping that of the Strømme syndrome including fetal autopsy results. Using family-based whole-exome sequencing, we identified truncating mutations in the centrosome gene CENPF in the two nonconsanguineous Caucasian sibling pairs. Compound heterozygous inheritance was confirmed in both families. Recently, mutations in this gene were shown to cause a fetal lethal phenotype, the phenotype and functional data being compatible with a human ciliopathy [Waters et al., 2015]. We show for the first time that Strømme syndrome is an autosomal-recessive disease caused by mutations in CENPF that can result in a wide phenotypic spectrum.