Developmental outcome of electroencephalographic findings in SYNGAP1 encephalopathy.

SYNGAP1 haploinsufficiency results in a developmental and epileptic encephalopathy (DEE) causing generalized epilepsies accompanied by a spectrum of neurodevelopmental symptoms. Concerning interictal epileptiform discharges (IEDs) in electroencephalograms (EEG), potential biomarkers have been postulated, including changes in background activity, fixation-off sensitivity (FOS) or eye closure sensitivity (ECS). In this study we clinically evaluate a new cohort of 36 SYNGAP1-DEE individuals. Standardized questionnaires were employed to collect clinical, electroencephalographic and genetic data. We investigated electroencephalographic findings, focusing on the cortical distribution of interictal abnormalities and their changes with age. Among the 36 SYNGAP1-DEE cases 18 presented variants in the SYNGAP1 gene that had never been previously reported. The mean age of diagnosis was 8 years and 8 months, ranging from 2 to 17 years, with 55.9% being male. All subjects had global neurodevelopmental/language delay and behavioral abnormalities; 83.3% had moderate to profound intellectual disability (ID), 91.7% displayed autistic traits, 73% experienced sleep disorders and 86.1% suffered from epileptic seizures, mainly eyelid myoclonia with absences (55.3%). A total of 63 VEEGs were revised, observing a worsening of certain EEG findings with increasing age. A disorganized background was observed in all age ranges, yet this was more common among older cases. The main IEDs were bilateral synchronous and asynchronous posterior discharges, accounting for ≥50% in all age ranges. Generalized alterations with maximum amplitude in the anterior region showed as the second most frequent IED (≥15% in all age ranges) and were also more common with increasing age. Finally, diffuse fast activity was much more prevalent in cases with 6 years or older. To the best of our knowledge, this is the first study to analyze EEG features across different age groups, revealing an increase in interictal abnormalities over infancy and adolescence. Our findings suggest that SYNGAP1 haploinsufficiency has complex effects in human brain development, some of which might unravel at different developmental stages. Furthermore, they highlight the potential of baseline EEG to identify candidate biomarkers and the importance of natural history studies to develop specialized therapies and clinical trials.

Elevated cholesterol in ATAD3 mutants is a compensatory mechanism that leads to membrane cholesterol aggregation.

Aberrant cholesterol metabolism causes neurological disease and neurodegeneration, and mitochondria have been linked to perturbed cholesterol homeostasis via the study of pathological mutations in the ATAD3 gene cluster. However, whether the cholesterol changes were compensatory or contributory to the disorder was unclear, nor were the effects on cell membranes or the wider cell known. Using patient-derived cells we show that cholesterol perturbation is a conserved feature of pathological ATAD3 variants that is accompanied by an expanded lysosome population containing membrane whorls characteristic of lysosomal storage diseases. Lysosomes are also more numerous in Drosophila neural progenitor cells expressing mutant Atad3, which exhibit abundant membrane-bound cholesterol aggregates, many of which co-localize with lysosomes. Using nutrient restriction and cholesterol supplementation, we show that the Drosophila Atad3 mutant displays heightened cholesterol dependence. Collectively, these findings suggest elevated cholesterol enhances tolerance to pathological ATAD3 variants, at a cost of inducing cholesterol aggregation in membranes, which lysosomal clearance only partly mitigates.

Genetic Heterogeneity Underlying Phenotypes with Early-Onset Cerebellar Atrophy.

Cerebellar atrophy (CA) is a frequent neuroimaging finding in paediatric neurology, usually associated with cerebellar ataxia. The list of genes involved in hereditary forms of CA is continuously growing and reveals its genetic complexity. We investigated ten cases with early-onset cerebellar involvement with and without ataxia by exome sequencing or by a targeted panel with 363 genes involved in ataxia or spastic paraplegia. Novel variants were investigated by in silico or experimental approaches. Seven probands carry causative variants in well-known genes associated with CA or cerebellar hypoplasia: SETX, CACNA1G, CACNA1A, CLN6, CPLANE1, and TBCD. The remaining three cases deserve special attention; they harbour variants in MAST1, PI4KA and CLK2 genes. MAST1 is responsible for an ultrarare condition characterised by global developmental delay and cognitive decline; our index case added ataxia to the list of concomitant associated symptoms. PIK4A is mainly related to hypomyelinating leukodystrophy; our proband presented with pure spastic paraplegia and normal intellectual capacity. Finally, in a patient who suffers from mild ataxia with oculomotor apraxia, the de novo novel CLK2 c.1120T>C variant was found. The protein expression of the mutated protein was reduced, which may indicate instability that would affect its kinase activity.

Environmental health knowledge of healthcare professionals: Instrument development and validation using the Rasch model.

INTRODUCTION: environmental risk factors constitute a major public health issue, calling for preventive actions and interventions at multiple levels. An important step in this direction is increasing the environmental health (EH) knowledge of the healthcare professionals. In this context, tools designed to measure such knowledge are of imperative importance. The aim of the present study was to develop an EH knowledge tool for healthcare professionals. METHODS: a group of experts defined the knowledge areas of the EH tool and their corresponding items. An online pilot and a validation study were performed. Internal consistency reliability was measured with the Kuder-Richardson 20 (KR-20) estimate, the construct validity and uni-dimensionality of the tool were assessed with the Rasch model. Known-groups validity was analysed with the two-sample t-test. RESULTS: a total of n = 151 and n = 444 healthcare professionals and end-year medical and nursing students, participated in the pilot and the validation study, respectively. The resulting 33-item EH knowledge questionnaire for healthcare professionals (EHKQ-HP) obtained a KR-20 = 0.82. The scale is uni-dimensional. Its construct validity was verified, and its items cover a wide range of difficulties. Separation statistics were adequate and known-groups behaved as hypothesized. CONCLUSIONS: the EHKQ-HP is a valuable resource for measuring the EH knowledge of the healthcare professionals. As such it will be useful in detecting EH knowledge gaps, and helping public health agents in making informed decisions when developing interventions for increasing this very knowledge. This would consequently help in improving the health of the general population.

Experimental and Bioinformatic Insights into the Effects of Epileptogenic Variants on the Function and Trafficking of the GABA Transporter GAT-1.

In this article, we identified a novel epileptogenic variant (G307R) of the gene SLC6A1, which encodes the GABA transporter GAT-1. Our main goal was to investigate the pathogenic mechanisms of this variant, located near the neurotransmitter permeation pathway, and compare it with other variants located either in the permeation pathway or close to the lipid bilayer. The mutants G307R and A334P, close to the gates of the transporter, could be glycosylated with variable efficiency and reached the membrane, albeit inactive. Mutants located in the center of the permeation pathway (G297R) or close to the lipid bilayer (A128V, G550R) were retained in the endoplasmic reticulum. Applying an Elastic Network Model, to these and to other previously characterized variants, we found that G307R and A334P significantly perturb the structure and dynamics of the intracellular gate, which can explain their reduced activity, while for A228V and G362R, the reduced translocation to the membrane quantitatively accounts for the reduced activity. The addition of a chemical chaperone (4-phenylbutyric acid, PBA), which improves protein folding, increased the activity of GAT-1WT, as well as most of the assayed variants, including G307R, suggesting that PBA might also assist the conformational changes occurring during the alternative access transport cycle.

Mutations, Genes, and Phenotypes Related to Movement Disorders and Ataxias.

Our clinical series comprises 124 patients with movement disorders (MDs) and/or ataxia with cerebellar atrophy (CA), many of them showing signs of neurodegeneration with brain iron accumulation (NBIA). Ten NBIA genes are accepted, although isolated cases compatible with abnormal brain iron deposits are known. The patients were evaluated using standardised clinical assessments of ataxia and MDs. First, NBIA genes were analysed by Sanger sequencing and 59 patients achieved a diagnosis, including the detection of the founder mutation PANK2 p.T528M in Romani people. Then, we used a custom panel MovDisord and/or exome sequencing; 29 cases were solved with a great genetic heterogeneity (34 different mutations in 23 genes). Three patients presented brain iron deposits with Fe-sensitive MRI sequences and mutations in FBXO7, GLB1, and KIF1A, suggesting an NBIA-like phenotype. Eleven patients showed very early-onset ataxia and CA with cortical hyperintensities caused by mutations in ITPR1, KIF1A, SPTBN2, PLA2G6, PMPCA, and PRDX3. The novel variants were investigated by structural modelling, luciferase analysis, transcript/minigenes studies, or immunofluorescence assays. Our findings expand the phenotypes and the genetics of MDs and ataxias with early-onset CA and cortical hyperintensities and highlight that the abnormal brain iron accumulation or early cerebellar gliosis may resembling an NBIA phenotype.

Enterovirus D68 Causing Acute Respiratory Infection: Clinical Characteristics and Differences With Acute Respiratory Infections Associated With Enterovirus Non-D68.

BACKGROUND: Enterovirus (EV) D68 is mainly associated with acute respiratory infection (ARI). Since 2014, when outbreaks in different countries were observed, this emerging virus was considered a potential threat to public health. METHODS: During 2015-2017, the presence of enterovirus RNA was investigated in all respiratory samples of children younger than 15 years of age with ARI, obtained for virologic studies in the Pediatric Emergency Care Units and wards of 2 hospitals in Gipuzkoa (Spain), using a commercial multiplex real-time polymerase chain reaction. When enterovirus was detected, a polymerase chain reaction to amplify a specific viral polyprotein (VP1) gene region of EV-D68 was performed. RESULTS: In 2016, EV-D68 circulation was associated to ARI, with the highest incidence in the spring months. EV-D68 was detected in 44 children, mean age 30.1 ± 31.7 months old, 23 (52.3%) of them females and 17 (38.6%) with underlying respiratory medical conditions. Thirty-two patients (72%) required hospital admission, receiving the discharge diagnosis of recurrent wheezing (37.5%), asthmatic crisis (37.5%) or bronchiolitis (12.5%). Seven children (15.9%) needed the support of the pediatric intensive care unit. When coinfections were excluded, children with EV-D68 infection presented with increased work of breathing, recurrent wheezing or asthmatic crisis, more frequently than those with ARI associated with EV non-D68. Moreover, clinical outcomes (hospitalization, respiratory support) were more severe. All 44 EV-D68 strains detected belonged to lineage B3. CONCLUSIONS: EV-D68 circulated widely in Gipuzkoa during 2016 and was associated with severe ARI. In children with severe ARI of unknown etiology, the presence of EV-D68 should be considered.

Brain MRI abnormalities in muscular dystrophy due to FKRP mutations.

INTRODUCTION: FKRP mutations cause a muscular dystrophy which may present in the neonatal period (MDC1C) or later in life (LGMD2I). Intelligence and brain imaging have been previously reported as being normal in FKRP-associated muscular dystrophy, except in rare cases presenting with mental retardation associated with structural brain abnormalities. PATIENTS AND METHODS: We studied cerebral MRIs in twelve patients with FKRP-associated muscular dystrophy presenting in infancy or early childhood, at ages between 14 months and 43 years. Two patients had severe cognitive deficits, four had mild-moderate mental retardation and the rest were considered to have normal intelligence. All, but one were wheelchair-bound and 7 were mechanically ventilated. RESULTS: Brain MRI was abnormal in 9 of 12 patients. Brain atrophy was seen in 8 patients. One child had isolated ventricular enlargement at 4 years. Cortical atrophy involved predominantly temporal and frontal lobes and was most important at later ages. In two cases with serial images this atrophy seemed progressive. Three patients, two with severe and one with moderate mental retardation, showed structural abnormalities of the posterior fossa with hypoplasia of the vermis and pons, and cerebellar hemispheric cysts. These abnormalities were stable with time. Two of these three patients also showed diffuse white matter abnormalities in early childhood, which regressed with time. CONCLUSIONS: MRI abnormalities are common in patients with FKRP-associated muscular dystrophy presenting at birth or in early childhood. Progressive brain atrophy is the most frequent finding. Posterior fossa malformations and transient white matter changes may be seen in patients with associated mental retardation.

Cloning of the gene containing mutations that cause PARK8-linked Parkinson's disease.

Parkinson's disease (PD; OMIM #168600) is the second most common neurodegenerative disorder in the Western world and presents as a progressive movement disorder. The hallmark pathological features of PD are loss of dopaminergic neurons from the substantia nigra and neuronal intracellular Lewy body inclusions. Parkinsonism is typically sporadic in nature; however, several rare familial forms are linked to genetic loci, and the identification of causal mutations has provided insight into the disease process. PARK8, identified in 2002 by Funayama and colleagues, appears to be a common cause of familial PD. We describe here the cloning of a novel gene that contains missense mutations segregating with PARK8-linked PD in five families from England and Spain. Because of the tremor observed in PD and because a number of the families are of Basque descent, we have named this protein dardarin, derived from the Basque word dardara, meaning tremor.