Psychogenic non-epileptic (functional) seizures in adults with intellectual disability and epilepsy: A matched case-control study.

OBJECTIVE: To describe the characteristics of psychogenic non-epileptic (functional) seizures (PNES) in adults with epilepsy and intellectual disability (ID) and to establish differences and risk factors regarding psychosocial functioning between individuals with and without PNES. METHODS: Adults with ID and epilepsy living in epilepsy care facilities in The Netherlands were screened for PNES by a neurologist. A control group consisting of people with epilepsy and ID, without PNES, was matched according to age, sex, and level of ID. Objective data were retrieved retrospectively from clinical notes of the resident. Standardized questionnaires and tests, adjusted for people with ID, were obtained from participants and their nursing staff. Differences were analyzed using paired t tests, Wilcoxon signed-rank tests, or McNemar's tests, appropriate for matched case-control studies. Conditional logistic regression identified PNES risk factors. RESULTS: Five hundred forty individuals were screened, of which 42 had PNES (point prevalence 7.8%). In total, 35 cases and 35 controls gave consent. Proxy reports indicated that PNES impacted daily life in 79% by adjusting the individual's schedule, and caused minor injuries in one-third. Those with PNES were mainly female (69%); had a mild (46%) or moderate (37%) level of ID; showed more symptoms of depression (p = .024), anxiety (p = .030), self-injurious behavior (p = .015); and experienced more negative life events (p < .001). Clinically relevant predictors of PNES were the number of negative life events (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.12-2.53) and self-injurious behaviors (OR 5.27, 95% CI .97-28.81). SIGNIFICANCE: Previously, PNES in individuals with ID and epilepsy were described mainly as a reinforced behavioral pattern, due to limited associations with psychiatric disorders. Our results demonstrate that this population does show individual psychosocial vulnerabilities when measured with instruments adjusted for this population, as indicated by proxy reports from daily caregivers. Viewing PNES as an involuntary response, especially for stress-prone individuals with ID, could reduce stigma and improve treatment.

Clinical features and genotype-phenotype correlations in epilepsy patients with de novo DYNC1H1 variants.

OBJECTIVE: DYNC1H1 variants are involved on a disease spectrum from neuromuscular disorders to neurodevelopmental disorders. DYNC1H1-related epilepsy has been reported in small cohorts. We dissect the electroclinical features of 34 patients harboring de novo DYNC1H1 pathogenic variants, identify subphenotypes on the DYNC1H1-related epilepsy spectrum, and compare the genotype-phenotype correlations observed in our cohort with the literature. METHODS: Patients harboring de novo DYNC1H1 pathogenic variants were recruited through international collaborations. Clinical data were retrospectively collected. Latent class analysis was performed to identify subphenotypes. Multivariable binary logistic regression analysis was applied to investigate the association with DYNC1H1 protein domains. RESULTS: DYNC1H1-related epilepsy presented with infantile epileptic spasms syndrome (IESS) in 17 subjects (50%), and in 25% of these individuals the epileptic phenotype evolved into Lennox-Gastaut syndrome (LGS). In 12 patients (35%), focal onset epilepsy was defined. In two patients, the epileptic phenotype consisted of generalized myoclonic epilepsy, with a progressive phenotype in one individual harboring a frameshift variant. In approximately 60% of our cohort, seizures were drug-resistant. Malformations of cortical development were noticed in 79% of our patients, mostly on the lissencephaly-pachygyria spectrum, particularly with posterior predominance in a half of them. Midline and infratentorial abnormalities were additionally reported in 45% and 27% of subjects. We have identified three main classes of subphenotypes on the DYNC1H1-related epilepsy spectrum. SIGNIFICANCE: We propose a classification in which pathogenic de novo DYNC1H1 variants feature drug-resistant IESS in half of cases with potential evolution to LGS (Class 1), developmental and epileptic encephalopathy other than IESS and LGS (Class 2), or less severe focal or genetic generalized epilepsy including a progressive phenotype (Class 3). We observed an association between stalk domain variants and Class 1 phenotypes. The variants p.Arg309His and p.Arg1962His were common and associated with Class 1 subphenotype in our cohort. These findings may aid genetic counseling of patients with DYNC1H1-related epilepsy.

SCN1A-deficient excitatory neuronal networks display mutation-specific phenotypes.

Dravet syndrome is a severe epileptic encephalopathy, characterized by (febrile) seizures, behavioural problems and developmental delay. Eighty per cent of patients with Dravet syndrome have a mutation in SCN1A, encoding Nav1.1. Milder clinical phenotypes, such as GEFS+ (generalized epilepsy with febrile seizures plus), can also arise from SCN1A mutations. Predicting the clinical phenotypic outcome based on the type of mutation remains challenging, even when the same mutation is inherited within one family. This clinical and genetic heterogeneity adds to the difficulties of predicting disease progression and tailoring the prescription of anti-seizure medication. Understanding the neuropathology of different SCN1A mutations may help to predict the expected clinical phenotypes and inform the selection of best-fit treatments. Initially, the loss of Na+-current in inhibitory neurons was recognized specifically to result in disinhibition and consequently seizure generation. However, the extent to which excitatory neurons contribute to the pathophysiology is currently debated and might depend on the patient clinical phenotype or the specific SCN1A mutation. To examine the genotype-phenotype correlations of SCN1A mutations in relation to excitatory neurons, we investigated a panel of patient-derived excitatory neuronal networks differentiated on multi-electrode arrays. We included patients with different clinical phenotypes, harbouring various SCN1A mutations, along with a family in which the same mutation led to febrile seizures, GEFS+ or Dravet syndrome. We hitherto describe a previously unidentified functional excitatory neuronal network phenotype in the context of epilepsy, which corresponds to seizurogenic network prediction patterns elicited by proconvulsive compounds. We found that excitatory neuronal networks were affected differently, depending on the type of SCN1A mutation, but did not segregate according to clinical severity. Specifically, loss-of-function mutations could be distinguished from missense mutations, and mutations in the pore domain could be distinguished from mutations in the voltage sensing domain. Furthermore, all patients showed aggravated neuronal network responses at febrile temperatures compared with controls. Finally, retrospective drug screening revealed that anti-seizure medication affected GEFS+ patient- but not Dravet patient-derived neuronal networks in a patient-specific and clinically relevant manner. In conclusion, our results indicate a mutation-specific excitatory neuronal network phenotype, which recapitulates the foremost clinically relevant features, providing future opportunities for precision therapies.

Human KCNQ5 de novo mutations underlie epilepsy and intellectual disability.

We identified six novel de novo human KCNQ5 variants in children with motor/language delay, intellectual disability (ID), and/or epilepsy by whole exome sequencing. These variants, comprising two nonsense and four missense alterations, were functionally characterized by electrophysiology in HEK293/CHO cells, together with four previously reported KCNQ5 missense variants (Lehman A, Thouta S, Mancini GM, Naidu S, van Slegtenhorst M, McWalter K, Person R, Mwenifumbo J, Salvarinova R; CAUSES Study; EPGEN Study; Guella I, McKenzie MB, Datta A, Connolly MB, Kalkhoran SM, Poburko D, Friedman JM, Farrer MJ, Demos M, Desai S, Claydon T. Am J Hum Genet 101: 65-74, 2017). Surprisingly, all eight missense variants resulted in gain of function (GOF) due to hyperpolarized voltage dependence of activation or slowed deactivation kinetics, whereas the two nonsense variants were confirmed to be loss of function (LOF). One severe GOF allele (P369T) was tested and found to extend a dominant GOF effect to heteromeric KCNQ5/3 channels. Clinical presentations were associated with altered KCNQ5 channel gating: milder presentations with LOF or smaller GOF shifts in voltage dependence [change in voltage at half-maximal conduction (ΔV50) = ∼-15 mV] and severe presentations with larger GOF shifts in voltage dependence (ΔV50 = ∼-30 mV). To examine LOF pathogenicity, two Kcnq5 LOF mouse lines were created with CRISPR/Cas9. Both lines exhibited handling- and thermal-induced seizures and abnormal cortical EEGs consistent with epileptiform activity. Our study thus provides evidence for in vivo KCNQ5 LOF pathogenicity and strengthens the contribution of both LOF and GOF mutations to global pediatric neurological impairment, including ID/epilepsy.NEW & NOTEWORTHY Six novel de novo human KCNQ5 variants were identified from children with neurodevelopmental delay, intellectual disability, and/or epilepsy. Expression of these variants along with four previously reported KCNQ5 variants from a similar cohort revealed GOF potassium channels, negatively shifted in V50 of activation and/or delayed deactivation kinetics. GOF is extended to KCNQ5/3 heteromeric channels, making these the predominant channels affected in heterozygous de novo patients. Kcnq5 LOF mice exhibited seizures, consistent with in vivo pathogenicity.

People with epilepsy and intellectual disability: More than a sum of two conditions.

BACKGROUND: Around 25% of people with Intellectual Disability (PwID) have comorbid epilepsy with seizures in up to two-thirds being drug-resistant. Little is known of the general characteristics and prescribing practices to this population. AIM: Describe and compare characteristics of two cohorts of PwID and epilepsy in two different countries to inform clinical practice better. METHOD: An explorative, retrospective, case-note review in a specialist ID community service in England and in an expert center for PwID and epilepsy in the Netherlands was conducted. Information on ID severity, medical/behavioral/psychiatric/neurodevelopmental/genetic comorbidities, psychotropic, and antiepileptic drugs (AEDs) for each cohort was collected. FINDINGS: The English cohort consisted of 167 people (98 males; age range 18-73 years; mild/moderate ID- 35%) and the Dutch cohort of 189 people (111 males; age range 18-85 years; mild/moderate ID - 51%). The two cohorts were comparable in their baseline characteristics. The Dutch had higher rates of physical comorbidity, but less mental or behavioral disorders and were more likely to be on anti-psychotic medication. The mean dosages between three most common AEDs prescribed were similar. The most frequently prescribed drug in both centers is valproate. Three-quarters of the Dutch were on three or more AEDs compared to a third in the English cohort. CONCLUSIONS: Structured description of the characteristics, differences, and commonalities of PwID, treatment, and services of both countries is presented. This is the first real-world study to reveal unique characteristics of managing epilepsy for a complex ID population. In particular, it highlights the considerable comorbid psychiatric burden and psychotropic prescribing.

Diagnostic exome sequencing in 100 consecutive patients with both epilepsy and intellectual disability.

OBJECTIVE: Epilepsy is highly prevalent among patients with intellectual disability (ID), and seizure control is often difficult. Identification of the underlying etiology in this patient group is important for daily clinical care. We assessed the diagnostic yield of whole exome sequencing (WES). In addition, we evaluated which clinical characteristics influence the likelihood of identifying a genetic cause and we assessed the potential impact of the genetic diagnosis on (antiepileptic) treatment strategy. METHODS: One hundred patients with both unexplained epilepsy and (borderline) ID (intelligence quotient ≤ 85) were included. All patients were evaluated by a clinical geneticist, a (pediatric) neurologist, and/or a specialist ID physician. WES analysis was performed in two steps. In step 1, analysis was restricted to the latest versions of ID and/or epilepsy gene panels. In step 2, exome analysis was extended to all genes (so-called full exome analysis). The results were classified according to the American College of Medical Genetics and Genomics guidelines. RESULTS: In 58 patients, the diagnostic WES analysis reported one or more variant(s). In 25 of the 100 patients, these were classified as (likely) pathogenic, in 24 patients as variants of uncertain significance, and in the remaining patients the variant was most likely not related to the phenotype. In 10 of 25 patients (40%) with a (likely) pathogenic variant, the genetic diagnosis might have an impact on the treatment strategy in the future. SIGNIFICANCE: This study illustrates the clinical diagnostic relevance of WES for patients with both epilepsy and ID. It also demonstrates that implementing WES diagnostics might have impact on the (antiepileptic) treatment strategy in this population. Confirmation of variants of uncertain significance in (candidate) genes may further increase the yield.

Mood, anxiety, and perceived quality of life in adults with epilepsy and intellectual disability.

OBJECTIVE: Depression and anxiety symptoms are common among patients with epilepsy, but are relatively under-researched in patients with both epilepsy and intellectual disability (ID). The aim was to investigate whether epilepsy and ID characteristics are associated with mood, anxiety, and quality of life. MATERIALS AND METHODS: Adult patients with epilepsy and ID who rely on tertiary epilepsy care were included (N = 189). Mood, anxiety, and quality of life were assessed by standardized questionnaires. Epilepsy and ID characteristics were retrieved from patient charts or determined by psychometric instruments. RESULTS: Elevated levels of depressive and anxiety symptoms were present in 21.7% and 12.7%, respectively. Anxiety was significantly associated with a focal epilepsy type and ID domain discrepancy (substantial difference between two domains of adaptive behavior), but was negatively related to seizure frequency and drug load of mood-stabilizing antiepileptic drugs. Depressive symptoms were not significantly related to epilepsy characteristics, but a severe ID and ID domain discrepancy was associated with more depressive symptoms. Quality of life was significantly worse in those with multiple seizure types and ID domain discrepancy. CONCLUSION: Whereas anxiety and quality of life are associated with individual epilepsy characteristics, this could not be confirmed for depressive symptoms in patients with epilepsy and ID, despite its high prevalence.

Defining the phenotypic spectrum of SLC6A1 mutations.

OBJECTIVE: Pathogenic SLC6A1 variants were recently described in patients with myoclonic atonic epilepsy (MAE) and intellectual disability (ID). We set out to define the phenotypic spectrum in a larger cohort of SCL6A1-mutated patients. METHODS: We collected 24 SLC6A1 probands and 6 affected family members. Four previously published cases were included for further electroclinical description. In total, we reviewed the electroclinical data of 34 subjects. RESULTS: Cognitive development was impaired in 33/34 (97%) subjects; 28/34 had mild to moderate ID, with language impairment being the most common feature. Epilepsy was diagnosed in 31/34 cases with mean onset at 3.7 years. Cognitive assessment before epilepsy onset was available in 24/31 subjects and was normal in 25% (6/24), and consistent with mild ID in 46% (11/24) or moderate ID in 17% (4/24). Two patients had speech delay only, and 1 had severe ID. After epilepsy onset, cognition deteriorated in 46% (11/24) of cases. The most common seizure types were absence, myoclonic, and atonic seizures. Sixteen cases fulfilled the diagnostic criteria for MAE. Seven further patients had different forms of generalized epilepsy and 2 had focal epilepsy. Twenty of 31 patients became seizure-free, with valproic acid being the most effective drug. There was no clear-cut correlation between seizure control and cognitive outcome. Electroencephalography (EEG) findings were available in 27/31 patients showing irregular bursts of diffuse 2.5-3.5 Hz spikes/polyspikes-and-slow waves in 25/31. Two patients developed an EEG pattern resembling electrical status epilepticus during sleep. Ataxia was observed in 7/34 cases. We describe 7 truncating and 18 missense variants, including 4 recurrent variants (Gly232Val, Ala288Val, Val342Met, and Gly362Arg). SIGNIFICANCE: Most patients carrying pathogenic SLC6A1 variants have an MAE phenotype with language delay and mild/moderate ID before epilepsy onset. However, ID alone or associated with focal epilepsy can also be observed.

Evaluation of perampanel in patients with intellectual disability and epilepsy.

INTRODUCTION: Initial registration studies of perampanel (PMP), an AMPA receptor antagonist, have now been followed up by 'clinical' studies that confirmed its efficacy and safety in patients with refractory epilepsy. Publications on the use of PMP among patients with intellectual disability (ID) are still limited. This study extends our knowledge with respect to the relevance of PMP for patients with both ID and epilepsy, and furthermore specifies the behavioral side effects of PMP in this specific population. METHODS: Retrospective evaluation of medical records at 3, 6 and 12months of follow-up after the initial start of PMP. RESULTS: 62 patients were included. 21 patients (33.9%) were female. All patients had complete data of 6months follow-up and we were able to review 42 patients with a 1-year follow-up. Level of ID varied from borderline to profound, and mild ID was most common (43.5%). The mean maximum daily dosage of PMP was 5.6mg (range 1-12mg). Retention rates for PMP were 87.1% and 67.7% after three and six months. A trend indicated a longer mean retention time in patients with a more severe ID (borderline-mild-moderate ID: 205days, severe-profound ID: 275days). Seizure reduction was achieved in 53.2%. 36 patients (58.1%) experienced adverse effects, 80.6% of those within 3months. 45.2% of the patients experienced somatic adverse effects. Most common were fatigue & sleep problems, motor problems & unsteadiness, and gastrointestinal problems. Behavioral adverse effects were present in 40.3%. Most common were aggression, agitated behavior, disruptive behavior, and mood symptoms. Reasons for discontinuation of PMP were lack of efficacy in 14.8%, intolerable adverse effects in 44.4%, and a combination of both in 40.7%. Altogether, 24.2% (15/62) of the patients achieved seizure reduction without experiencing adverse effects, though none reached seizure freedom. CONCLUSIONS: The use of PMP might lead to an effective seizure reduction without adverse effects in a minority of patients with both epilepsy and ID. Pre-existing behavioral problems or polypharmacy do not predict the occurrence of additional behavioral adverse effects, implying that these patients need not be excluded from the introduction of PMP when clinically indicated. Patients should, ideally, be monitored at a multidisciplinary clinic.

Mutations in BICD2, which encodes a golgin and important motor adaptor, cause congenital autosomal-dominant spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a heterogeneous group of neuromuscular disorders caused by degeneration of lower motor neurons. Although functional loss of SMN1 is associated with autosomal-recessive childhood SMA, the genetic cause for most families affected by dominantly inherited SMA is unknown. Here, we identified pathogenic variants in bicaudal D homolog 2 (Drosophila) (BICD2) in three families afflicted with autosomal-dominant SMA. Affected individuals displayed congenital slowly progressive muscle weakness mainly of the lower limbs and congenital contractures. In a large Dutch family, linkage analysis identified a 9q22.3 locus in which exome sequencing uncovered c.320C>T (p.Ser107Leu) in BICD2. Sequencing of 23 additional families affected by dominant SMA led to the identification of pathogenic variants in one family from Canada (c.2108C>T [p.Thr703Met]) and one from the Netherlands (c.563A>C [p.Asn188Thr]). BICD2 is a golgin and motor-adaptor protein involved in Golgi dynamics and vesicular and mRNA transport. Transient transfection of HeLa cells with all three mutant BICD2 cDNAs caused massive Golgi fragmentation. This observation was even more prominent in primary fibroblasts from an individual harboring c.2108C>T (p.Thr703Met) (affecting the C-terminal coiled-coil domain) and slightly less evident in individuals with c.563A>C (p.Asn188Thr) (affecting the N-terminal coiled-coil domain). Furthermore, BICD2 levels were reduced in affected individuals and trapped within the fragmented Golgi. Previous studies have shown that Drosophila mutant BicD causes reduced larvae locomotion by impaired clathrin-mediated synaptic endocytosis in neuromuscular junctions. These data emphasize the relevance of BICD2 in synaptic-vesicle recycling and support the conclusion that BICD2 mutations cause congenital slowly progressive dominant SMA.

A systematic review of neuropsychiatric comorbidities in patients with both epilepsy and intellectual disability.

Epilepsy is a neurological condition that is particularly common in people with intellectual disability (ID). The care for people with both epilepsy and ID is often complicated by the presence of neuropsychiatric disorders, defined as psychiatric symptoms, psychiatric disorders, and behavioral problems. The aim of this study was to investigate associations between epilepsy or epilepsy-related factors and neuropsychiatric comorbidities in patients with ID and between ID and neuropsychiatric comorbidities in patients with epilepsy. We performed a systematic review of the literature, published between January 1995 and January 2015 and retrieved from PubMed/Medline, PsycINFO, and ERIC and assessed the risk of bias using the SIGN-50 methodology. Forty-two studies were identified, fifteen of which were assessed as having a low or acceptable risk-of-bias evaluation. Neuropsychiatric comorbidities were examined in relation to epilepsy in nine studies; in relation to epilepsy-related factors, such as seizure activity, seizure type, and medication in four studies; and in relation to the presence and degree of ID in five studies. We conclude that the presence of epilepsy only was not a clear determinant of neuropsychiatric comorbidity in patients with ID, although a tendency towards negative mood symptoms was identified. Epilepsy-related factors indicating a more severe form of epilepsy were associated with neuropsychiatric comorbidity as was the presence of ID as compared to those without ID in patients with epilepsy, although this should be validated in future research. A large proportion of the studies in this area is associated with a substantial risk of bias. There is a need for high quality studies using standardized methods to enable clear conclusions to be drawn that might assist in improving the quality of care for this population.

Whole-genome sequencing reveals a coding non-pathogenic variant tagging a non-coding pathogenic hexanucleotide repeat expansion in C9orf72 as cause of amyotrophic lateral sclerosis.

Motor neuron degeneration in amyotrophic lateral sclerosis (ALS) has a familial cause in 10% of patients. Despite significant advances in the genetics of the disease, many families remain unexplained. We performed whole-genome sequencing in five family members from a pedigree with autosomal-dominant classical ALS. A family-based elimination approach was used to identify novel coding variants segregating with the disease. This list of variants was effectively shortened by genotyping these variants in 2 additional unaffected family members and 1500 unrelated population-specific controls. A novel rare coding variant in SPAG8 on chromosome 9p13.3 segregated with the disease and was not observed in controls. Mutations in SPAG8 were not encountered in 34 other unexplained ALS pedigrees, including 1 with linkage to chromosome 9p13.2-23.3. The shared haplotype containing the SPAG8 variant in this small pedigree was 22.7 Mb and overlapped with the core 9p21 linkage locus for ALS and frontotemporal dementia. Based on differences in coverage depth of known variable tandem repeat regions between affected and non-affected family members, the shared haplotype was found to contain an expanded hexanucleotide (GGGGCC)(n) repeat in C9orf72 in the affected members. Our results demonstrate that rare coding variants identified by whole-genome sequencing can tag a shared haplotype containing a non-coding pathogenic mutation and that changes in coverage depth can be used to reveal tandem repeat expansions. It also confirms (GGGGCC)n repeat expansions in C9orf72 as a cause of familial ALS.

Evidence for an oligogenic basis of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with a substantial heritable component. In pedigrees affected by its familial form, incomplete penetrance is often observed. We hypothesized that this could be caused by a complex inheritance of risk variants in multiple genes. Therefore, we screened 111 familial ALS (FALS) patients from 97 families, and large cohorts of sporadic ALS (SALS) patients and control subjects for mutations in TAR DNA-binding protein (TARDBP), fused in sarcoma/translated in liposarcoma (FUS/TLS), superoxide dismutase-1 (SOD1), angiogenin (ANG) and chromosome 9 open reading frame 72 (C9orf72). Mutations were identified in 48% of FALS families, 8% of SALS patients and 0.5% of control subjects. In five of the FALS families, we identified multiple mutations in ALS-associated genes. We detected FUS/TLS and TARDBP mutations in combination with ANG mutations, and C9orf72 repeat expansions with TARDBP, SOD1 and FUS/TLS mutations. Statistical analysis demonstrated that the presence of multiple mutations in FALS is in excess of what is to be expected by chance (P = 1.57 × 10(-7)). The most compelling evidence for an oligogenic basis was found in individuals with a p.N352S mutation in TARDBP, detected in five FALS families and three apparently SALS patients. Genealogical and haplotype analyses revealed that these individuals shared a common ancestor. We obtained DNA of 14 patients with this TARDBP mutation, 50% of whom had an additional mutation (ANG, C9orf72 or homozygous TARDBP). Hereby, we provide evidence for an oligogenic aetiology of ALS. This may have important implications for the interpretation of whole exome/genome experiments designed to identify new ALS-associated genes and for genetic counselling, especially of unaffected family members.

Autoantibodies to cytosolic 5'-nucleotidase 1A in inclusion body myositis.

OBJECTIVE: Sporadic inclusion body myositis (sIBM) is an inflammatory myopathy characterized by both degenerative and autoimmune features. In contrast to other inflammatory myopathies, myositis-specific autoantibodies had not been found in sIBM patients until recently. We used human skeletal muscle extracts as a source of antigens to detect autoantibodies in sIBM and to characterize the corresponding antigen. METHODS: Autoantibodies to skeletal muscle antigens were detected by immunoblotting. The target antigen was immunoaffinity-purified from skeletal muscle extracts and characterized by mass spectrometry. A cDNA encoding this protein was cloned and expressed in vitro, and its recognition by patient sera was analyzed in an immunoprecipitation assay. Epitopes were mapped using microarrays of overlapping peptides. RESULTS: An Mr 44,000 polypeptide (Mup44) was frequently targeted by sIBM autoantibodies. The target protein was purified, and subsequent mass spectrometry analysis revealed that Mup44 is the cytosolic 5'-nucleotidase 1A (cN1A). By immunoprecipitation of recombinant cN1A, high concentrations of anti-Mup44 autoantibodies were detected in 33% of sIBM patient sera, whereas their prevalence in dermatomyositis, polymyositis, and other neuromuscular disorders appeared to be rare (4.2%, 4.5%, and 3.2%, respectively). Low concentrations of anti-Mup44 antibodies were found in myositis as well as other neuromuscular disorders, but not in healthy controls. Three major autoepitope regions of cN1A were mapped by using microarrays containing a set of overlapping peptides covering the complete cN1A amino acid sequence. INTERPRETATION: Anti-Mup44 autoantibodies, which are targeted to cN1A, represent the first serological biomarker for sIBM and may facilitate the diagnosis of this type of myositis.

Mutations in potassium channel kcnd3 cause spinocerebellar ataxia type 19.

OBJECTIVE: To identify the causative gene for the neurodegenerative disorder spinocerebellar ataxia type 19 (SCA19) located on chromosomal region 1p21-q21. METHODS: Exome sequencing was used to identify the causal mutation in a large SCA19 family. We then screened 230 ataxia families for mutations located in the same gene (KCND3, also known as Kv4.3) using high-resolution melting. SCA19 brain autopsy material was evaluated, and in vitro experiments using ectopic expression of wild-type and mutant Kv4.3 were used to study protein localization, stability, and channel activity by patch-clamping. RESULTS: We detected a T352P mutation in the third extracellular loop of the voltage-gated potassium channel KCND3 that cosegregated with the disease phenotype in our original family. We identified 2 more novel missense mutations in the channel pore (M373I) and the S6 transmembrane domain (S390N) in 2 other ataxia families. T352P cerebellar autopsy material showed severe Purkinje cell degeneration, with abnormal intracellular accumulation and reduced protein levels of Kv4.3 in their soma. Ectopic expression of all mutant proteins in HeLa cells revealed retention in the endoplasmic reticulum and enhanced protein instability, in contrast to wild-type Kv4.3 that was localized on the plasma membrane. The regulatory ß subunit Kv channel interacting protein 2 was able to rescue the membrane localization and the stability of 2 of the 3 mutant Kv4.3 complexes. However, this either did not restore the channel function of the membrane-located mutant Kv4.3 complexes or restored it only partially. INTERPRETATION: KCND3 mutations cause SCA19 by impaired protein maturation and/or reduced channel function.

The clinical and pathological phenotype of C9ORF72 hexanucleotide repeat expansions.

There is increasing evidence that frontotemporal dementia and amyotrophic lateral sclerosis are part of a disease continuum. Recently, a hexanucleotide repeat expansion in C9orf72 was identified as a major cause of both sporadic and familial frontotemporal dementia and amyotrophic lateral sclerosis. The aim of this study was to investigate clinical and neuropathological characteristics of hexanucleotide repeat expansions in C9orf72 in a large cohort of Dutch patients with frontotemporal dementia. Repeat expansions were successfully determined in a cohort of 353 patients with sporadic or familial frontotemporal dementia with or without amyotrophic lateral sclerosis, and 522 neurologically normal controls. Immunohistochemistry was performed in a series of 10 brains from patients carrying expanded repeats using a panel of antibodies. In addition, the presence of RNA containing GGGGCC repeats in paraffin-embedded sections of post-mortem brain tissue was investigated using fluorescence in situ hybridization with a locked nucleic acid probe targeting the GGGGCC repeat. Hexanucleotide repeat expansions in C9orf72 were found in 37 patients with familial (28.7%) and five with sporadic frontotemporal dementia (2.2%). The mean age at onset was 56.9 ± 8.3 years (range 39-76), and disease duration 7.6 ± 4.6 years (range 1-22). The clinical phenotype of these patients varied between the behavioural variant of frontotemporal dementia (n = 34) and primary progressive aphasia (n = 8), with concomitant amyotrophic lateral sclerosis in seven patients. Predominant temporal atrophy on neuroimaging was present in 13 of 32 patients. Pathological examination of the 10 brains from patients carrying expanded repeats revealed frontotemporal lobar degeneration with neuronal transactive response DNA binding protein-positive inclusions of variable type, size and morphology in all brains. Fluorescence in situ hybridization analysis of brain material from patients with the repeat expansion, a microtubule-associated protein tau or a progranulin mutation, and controls did not show RNA-positive inclusions specific for brains with the GGGGCC repeat expansion. The hexanucleotide repeat expansion in C9orf72 is an important cause of frontotemporal dementia with and without amyotrophic lateral sclerosis, and is sometimes associated with primary progressive aphasia. Neuropathological hallmarks include neuronal and glial inclusions, and dystrophic neurites containing transactive response DNA binding protein. Future studies are needed to explain the wide variation in clinical presentation.

Smoking, alcohol consumption, and the risk of amyotrophic lateral sclerosis: a population-based study.

Smoking has been posited as a possible risk factor for amyotrophic lateral sclerosis (ALS), but large population-based studies of patients with incident disease are still needed. The authors performed a population-based case-control study in the Netherlands between 2006 and 2009, including 494 patients with incident ALS and 1,599 controls. To prove the relevance of population-based incidence cohorts in case-control studies, the authors compared results with those from cohorts including patients with prevalent ALS and referral patients. Subjects were sent a questionnaire. Multivariate analyses showed an increased risk of ALS among current smokers (odds ratio = 1.38, 95% confidence interval (CI): 1.02, 1.88) in the incident patient group only. Cox regression models showed that current smoking was also independently associated with shorter survival (hazard ratio = 1.51, 95% CI: 1.07, 2.15), explaining the lack of association in the prevalent and referral patient groups. Current alcohol consumption was associated with a reduced risk of ALS (incident patient group: odds ratio = 0.52, 95% CI: 0.40, 0.75). These findings indicate that current smoking is associated with an increased risk of ALS, as well as a worse prognosis, and alcohol consumption is associated with a reduced risk of ALS, further corroborating the role of lifestyle factors in the pathogenesis of ALS. The importance of population-based incident patient cohorts in identifying risk factors is highlighted by this study.

Angiogenin variants in Parkinson disease and amyotrophic lateral sclerosis.

OBJECTIVE: Several studies have suggested an increased frequency of variants in the gene encoding angiogenin (ANG) in patients with amyotrophic lateral sclerosis (ALS). Interestingly, a few ALS patients carrying ANG variants also showed signs of Parkinson disease (PD). Furthermore, relatives of ALS patients have an increased risk to develop PD, and the prevalence of concomitant motor neuron disease in PD is higher than expected based on chance occurrence. We therefore investigated whether ANG variants could predispose to both ALS and PD. METHODS: We reviewed all previous studies on ANG in ALS and performed sequence experiments on additional samples, which allowed us to analyze data from 6,471 ALS patients and 7,668 controls from 15 centers (13 from Europe and 2 from the USA). We sequenced DNA samples from 3,146 PD patients from 6 centers (5 from Europe and 1 from the USA). Statistical analysis was performed using the variable threshold test, and the Mantel-Haenszel procedure was used to estimate odds ratios. RESULTS: Analysis of sequence data from 17,258 individuals demonstrated a significantly higher frequency of ANG variants in both ALS and PD patients compared to control subjects (p = 9.3 × 10(-6) for ALS and p = 4.3 × 10(-5) for PD). The odds ratio for any ANG variant in patients versus controls was 9.2 for ALS and 6.7 for PD. INTERPRETATION: The data from this multicenter study demonstrate that there is a strong association between PD, ALS, and ANG variants. ANG is a genetic link between ALS and PD.

Efficacy and tolerability of brivaracetam in patients with intellectual disability and epilepsy.

Patients with intellectual disability (ID) are often excluded from clinical trials, and little is known about the best approach to treat their epilepsy. Brivaracetam (BRV) is a new antiepileptic drug (AED) for adjunctive treatment in patients with focal-onset seizures with or without secondary generalization. We analyzed the efficacy and tolerability of BRV in patients with ID and epilepsy who either had or had not previously received treatment with levetiracetam (LEV). Data on efficacy and tolerability were retrospectively collected. After the initial start of BRV in our tertiary epilepsy center, we analyzed medical records at 0, 3, 6 and 12 months of follow-up. 116 patients were included (mean age = 34.9 years, 44% female). All had complete data of 3-month follow-up, 76 of 6-month follow-up, and 39 patients of 1-year follow-up. Median starting dose of BRV was 50.0 mg/day and the mean number of concomitant AEDs was 2.6. Seizure reduction and no side effects were reported in more than half of all patients. The most reported side effects were somnolence, dizziness and aggression. Retention rates for BRV were 84.4%, 75.5% and 58.1% after 3, 6 and 12 months, respectively. Seizure reduction and side effects did not differ significantly between the groups with or without previous LEV treatment. We demonstrate that BRV is effective and well tolerated in patients with epilepsy and ID, even in those where previous LEV treatment failed.

Monitoring disease progression using high-density motor unit number estimation in amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS), progressive motor neuron loss causes severe weakness. Functional measurements tend to underestimate the underlying pathology because of collateral reinnervation. A more direct marker of lower motor neuron loss is of significant importance. We evaluated high-density motor unit number estimation (MUNE), as compared with the ALS Functional Rating Scale (ALSFRS) and maximal compound muscle action potential (CMAP) amplitude, for monitoring and classifying disease progression. MUNE showed good reproducibility (intraclass correlation coefficient = 0.86). MUNE showed a significantly greater decrease than the ALSFRS, the Medical Research Council (MRC) scale, and CMAP amplitude. Patients could be stratified into groups with rapidly or slowly progressive disease based on a decrement in MUNE at 4 months from baseline; ALSFRS score at 8 months was significantly lower in the rapidly progressive group. MUNE was sensitive to motor neuron loss early in the disease course when compared to other clinical measures. Stratification of patients based on a decrease in MUNE seems feasible.