Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence

Genetic research; Nervous system diseases; PediatricsInvestigación genética; Enfermedades del sistema nervioso; PediatríaRecerca genètica; Malalties del sistema nerviós; PediatriaBackground Aminoacyl-tRNA synthetases (ARS) are key enzymes catalysing the first reactions in protein synthesis, with increasingly recognised pleiotropic roles in tumourgenesis, angiogenesis, immune response and lifespan. Germline mutations in several ARS genes have been associated with both recessive and dominant neurological diseases. Recently, patients affected with microcephaly, intellectual disability and ataxia harbouring biallelic variants in the seryl-tRNA synthetase encoded by seryl-tRNA synthetase 1 (SARS1) were reported. Methods We used exome sequencing to identify the causal variant in a patient affected by complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but without microcephaly. Complementation and serylation assays using patient’s fibroblasts and an Saccharomyces cerevisiae model were performed to examine this variant’s pathogenicity. Results A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site. Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect. Fibroblasts showed an abnormal cell shape, arrested division and increased beta-galactosidase staining along with a senescence-associated secretory phenotype (raised interleukin-6, p21, p16 and p53 levels). Conclusion We refine the phenotypic spectrum and modes of inheritance of a newly described, ultrarare neurodevelopmental disorder, while unveiling the role of SARS1 as a regulator of cell growth, division and senescence.This study was supported by grants from the Undiagnosed Rare Disease programme URD-Cat (SLT002/16/00174) from the Generalitat de Catalunya, the Center for Biomedical Research on Rare Diseases (CIBERER) (ACCI19-759), the ASL-HSP France and the Hesperia Foundation to AP. This study was also funded by the Instituto de Salud Carlos III and ‘Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea, una manera de hacer Europa’ (FIS PI20/00758) to CC and ‘La Marató de TV3’ Foundation (202006-30) to CC and AP. This study was also funded by Instituto de Salud Carlos III (Sara Borrell programme, CD19/00221) to EV, the Spanish Ministerio de Economia, Industria y Competividad (Juan de la Cierva programme FJCI-2016-28811) to EV, and the Center for Biomedical Research on Rare Diseases (CIBERER) to MR and NL. This study was supported by the French National Programme Investissement d’Avenir administered by the ‘Agence National de la Recherche’ (ANR), ‘MitoCross’ Laboratory of Excellence (Labex), funded as ANR-10-IDEX-0002-02, the University of Strasbourg and CNRS (to HB, BS). The CERCA Programme/Generalitat de Catalunya provided institutional support. AP is member of the Undiagnosed Disease Network International (UDNI)

Biallelic PI4KA variants cause a novel neurodevelopmental syndrome with hypomyelinating leukodystrophy

Hypomyelinating leukodystrophy; Inborn errors of metabolism; PhosphoinositolLeucodistrofia hipomielinizante; Errores innatos del metabolismo; FosfoinositolLeucodistròfia hipomielinizant; Errors innats del metabolisme; FosfoinositolPhosphoinositides are lipids that play a critical role in processes such as cellular signalling, ion channel activity and membrane trafficking. When mutated, several genes that encode proteins that participate in the metabolism of these lipids give rise to neurological or developmental phenotypes. PI4KA is a phosphoinositide kinase that is highly expressed in the brain and is essential for life. Here we used whole exome or genome sequencing to identify 10 unrelated patients harbouring biallelic variants in PI4KA that caused a spectrum of conditions ranging from severe global neurodevelopmental delay with hypomyelination and developmental brain abnormalities to pure spastic paraplegia. Some patients presented immunological deficits or genito-urinary abnormalities. Functional analyses by western blotting and immunofluorescence showed decreased PI4KA levels in the patients’ fibroblasts. Immunofluorescence and targeted lipidomics indicated that PI4KA activity was diminished in fibroblasts and peripheral blood mononuclear cells. In conclusion, we report a novel severe metabolic disorder caused by PI4KA malfunction, highlighting the importance of phosphoinositide signalling in human brain development and the myelin sheath.We thank the CERCA Program/Generalitat de Catalunya for institutional support. This study was supported by grants from the Hesperia Foundation, the Asociación Española contra las Leucodistrofias (ALE-ELA España), the Autonomous Government of Catalonia (SGR 2017SGR1206 and PERIS program URD-Cat SLT002/16/00174) and the Center for Biomedical Research on Rare Diseases (CIBERER) (ACCI19-759 to A.P.). This study was also funded by Fundació La Marató de TV3 (595/C/2020) as well as Instituto de Salud Carlos III (FIS PI20/00758 to C.C.) (co-funded by European Regional Development Fund. ERDF, a way to build Europe). This study was also funded by the Instituto de Salud Carlos III (Rio Hortega, CM18/00145 to V.V.; PFIS, FI18/00141 to L.P.; and Sara Borrell, CD19/00221 to E.V.), co-funded by European Social Fund. ESF investing in your future; the Ministerio de Ciencia e Innovación y Universidades (Juan de la Cierva, FJCI-2016-28811 to E.V.), and the Center for Biomedical Research on Rare Diseases (CIBERER to M.R.). Sequencing and analysis of Patient 5 were performed by the Broad Institute of MIT and Harvard Center for Mendelian Genomics (Broad CMG) and were funded by the National Human Genome Research Institute, the National Eye Institute, the National Heart, Lung and Blood Institute grants UM1 HG008900 and R01 HG009141 and the Chan Zuckerberg Initiative to the Rare Genomes Project. This work was in part supported by the association ‘Connaître les Syndromes Cérébelleux’ (CSC). This research received funding specifically appointed to the Department of Medical Sciences from the Italian Ministry for Education, University and Research (Ministero dell’istruzione, dell’università e della ricerca-MIUR) under the programme ‘Dipartimenti di Eccellenza 2018-2022’ Project code D15D18000410001. Whole-exome sequencing was performed as part of the Autism Sequencing Consortium and was supported by the NIMH (MH111661). D.R.A. and A.P. are members of the Undiagnosed Disease Network International (UDNI)

Herpes simplex virus encephalitis is a trigger of brain autoimmunity

In 5 prospectively diagnosed patients with relapsing post-herpes simplex encephalitis (HSE), N-methyl-D-aspartate receptor (NMDAR) antibodies were identified. Antibody synthesis started 1 to 4 weeks after HSE, preceding the neurological relapse. Three of 5 patients improved postimmunotherapy, 1 spontaneously, and 1 has started to improve. Two additional patients with NMDAR antibodies, 9 with unknown neuronal surface antibodies, and 1 with NMDAR and unknown antibodies, were identified during retrospective assessment of 34 HSE patients; the frequency of autoantibodies increased over time (serum, p=0.004; cerebrospinal fluid, p=0.04). The 3 retrospectively identified NMDAR antibody-positive patients also had evidence of relapsing post-HSE. Overall, these findings indicate that HSE triggers NMDAR antibodies and potentially other brain autoimmunity

Biallelic PI4KA variants cause a novel neurodevelopmental syndrome with hypomyelinating leukodystrophy

Phosphoinositides are lipids that play a critical role in processes such as cellular signalling, ion channel activity and membrane trafficking. When mutated, several genes that encode proteins that participate in the metabolism of these lipids give rise to neurological or developmental phenotypes. PI4KA is a phosphoinositide kinase that is highly expressed in the brain and is essential for life. Here we used whole exome or genome sequencing to identify 10 unrelated patients harbouring biallelic variants in PI4KA that caused a spectrum of conditions ranging from severe global neurodevelopmental delay with hypomyelination and developmental brain abnormalities to pure spastic paraplegia. Some patients presented immunological deficits or genito-urinary abnormalities. Functional analyses by western blotting and immunofluorescence showed decreased PI4KA levels in the patients' fibroblasts. Immunofluorescence and targeted lipidomics indicated that PI4KA activity was diminished in fibroblasts and peripheral blood mononuclear cells. In conclusion, we report a novel severe metabolic disorder caused by PI4KA malfunction, highlighting the importance of phosphoinositide signalling in human brain development and the myelin sheath

Low Penetrance, Broad Resistance, and Favorable Outcome of Interleukin 12 Receptor β1 Deficiency: Medical and Immunological Implications

The clinical phenotype of interleukin 12 receptor β1 chain (IL-12Rβ1) deficiency and the function of human IL-12 in host defense remain largely unknown, due to the small number of patients reported. We now report 41 patients with complete IL-12Rβ1 deficiency from 17 countries. The only opportunistic infections observed, in 34 patients, were of childhood onset and caused by weakly virulent Salmonella or Mycobacteria (Bacille Calmette-Guérin -BCG- and environmental Mycobacteria). Three patients had clinical tuberculosis, one of whom also had salmonellosis. Unlike salmonellosis, mycobacterial infections did not recur. BCG inoculation and BCG disease were both effective against subsequent environmental mycobacteriosis, but not against salmonellosis. Excluding the probands, seven of the 12 affected siblings have remained free of case-definition opportunistic infection. Finally, only five deaths occurred in childhood, and the remaining 36 patients are alive and well. Thus, a diagnosis of IL-12Rβ1 deficiency should be considered in children with opportunistic mycobacteriosis or salmonellosis; healthy siblings of probands and selected cases of tuberculosis should also be investigated. The overall prognosis is good due to broad resistance to infection and the low penetrance and favorable outcome of infections. Unexpectedly, human IL-12 is redundant in protective immunity against most microorganisms other than Mycobacteria and Salmonella. Moreover, IL-12 is redundant for primary immunity to Mycobacteria and Salmonella in many individuals and for secondary immunity to Mycobacteria but not to Salmonella in most

Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment

VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved residues within the C terminus of the VAMP2 SNARE motif. Affected individuals carrying de novo non-synonymous variants involving the C-terminal region presented a more severe phenotype with additional neurological features, including central visual impairment, hyperkinetic movement disorder, and epilepsy or electroencephalography abnormalities. Reconstituted fusion involving a lipid-mixing assay indicated impairment in vesicle fusion as one of the possible associated disease mechanisms. The genetic synaptopathy caused by VAMP2 de novo mutations highlights the key roles of this gene in human brain development and function

Systematic Collaborative Reanalysis of Genomic Data Improves Diagnostic Yield in Neurologic Rare Diseases

Altres ajuts: Generalitat de Catalunya, Departament de Salut; Generalitat de Catalunya, Departament d'Empresa i Coneixement i CERCA Program; Ministerio de Ciencia e Innovación; Instituto Nacional de Bioinformática; ELIXIR Implementation Studies (CNAG-CRG); Centro de Investigaciones Biomédicas en Red de Enfermedades Raras; Centro de Excelencia Severo Ochoa; European Regional Development Fund (FEDER).Many patients experiencing a rare disease remain undiagnosed even after genomic testing. Reanalysis of existing genomic data has shown to increase diagnostic yield, although there are few systematic and comprehensive reanalysis efforts that enable collaborative interpretation and future reinterpretation. The Undiagnosed Rare Disease Program of Catalonia project collated previously inconclusive good quality genomic data (panels, exomes, and genomes) and standardized phenotypic profiles from 323 families (543 individuals) with a neurologic rare disease. The data were reanalyzed systematically to identify relatedness, runs of homozygosity, consanguinity, single-nucleotide variants, insertions and deletions, and copy number variants. Data were shared and collaboratively interpreted within the consortium through a customized Genome-Phenome Analysis Platform, which also enables future data reinterpretation. Reanalysis of existing genomic data provided a diagnosis for 20.7% of the patients, including 1.8% diagnosed after the generation of additional genomic data to identify a second pathogenic heterozygous variant. Diagnostic rate was significantly higher for family-based exome/genome reanalysis compared with singleton panels. Most new diagnoses were attributable to recent gene-disease associations (50.8%), additional or improved bioinformatic analysis (19.7%), and standardized phenotyping data integrated within the Undiagnosed Rare Disease Program of Catalonia Genome-Phenome Analysis Platform functionalities (18%)

Health-related quality of life and the burden of prolonged seizures in noninstitutionalized children with epilepsy

OBJECTIVE: This study aimed to provide information on the burden of illness and health-related quality of life (HRQoL) in children with epilepsy who experience prolonged acute convulsive seizures (PACS) in the community setting, and to investigate factors that may predict poor HRQoL in this population. METHODS: Noninstitutionalized children (aged 3-16 years) who had experienced at least one PACS within the past year and had currently prescribed PACS rescue medication were enrolled in a cross-sectional study in Germany, Italy, Spain, and the United Kingdom (Practices in Emergency and Rescue medication For Epilepsy managed with Community-administered Therapy 3 [PERFECT-3]). Clinicians, parents/guardians, and patients completed web-based questionnaires regarding clinical characteristics, PACS frequency, and day-to-day impairment. Patients' HRQoL was rated by clinicians, parents/guardians, and patients themselves using the 5-dimension EuroQol questionnaire (EQ-5D) and summarized as a utility score. Potential predictors of poor HRQoL were tested in individual univariate generalized linear models and a global multivariable model. RESULTS: Enrolled children (N = 286) had experienced 1-400 PACS (median: 4) in the past year. Clinicians reported that 216/281 patients (76.9%) had learning disabilities of varying severity. Mean EQ-5D utility scores rated by clinicians (n = 279), parents (n = 277), and patients (n = 85) were 0.52 (standard deviation: 0.41), 0.51 (0.39), and 0.74 (0.29), respectively. Increasing PACS frequency, increasing severity of learning disability, and specialist school attendance were significantly associated with decreasing EQ-5D utility score. In the multivariable model, having learning disabilities was the best predictor of poor HRQoL. SIGNIFICANCE: Health-related quality of life was very poor in many children with epilepsy whose PACS were managed with rescue medication in the community, with learning disability being the most powerful predictor of patients' HRQoL. Mean EQ-5D utility scores were lower (worse) than published values for many other chronic disorders, indicating that optimal treatment should involve helping children and their families to manage learning disabilities and day-to-day impairments, in addition to preventing seizures.status: publishe

Effect of rescue medication on seizure duration in non-institutionalized children with epilepsy

Objectives: characterize the real-world management of and outcomes for children with epilepsy receiving rescue medication for prolonged acute convulsive seizures (PACS) in the community.Methods: PERFECT-3 (Practices in Emergency and Rescue medication For Epilepsy managed with Community-administered Therapy 3) was a European, retrospective observational study. Eligible patients were non-institutionalized children with epilepsy aged 3-16 years who had experienced ≥1 PACS in the past year and had ≥1 currently prescribed PACS rescue medication. Investigators provided clinical assessments and parents/guardians completed questionnaires. Statistical tests were post hoc; p values are descriptive.Results: at enrollment (N = 286), most patients had prescriptions for diazepam (69.2%) and/or midazolam (55.9%); some had two (26.6%) or three (2.4%) prescribed rescue medications. Most patients experienced PACS despite regular anti-epilepsy medication. According to parents, the average duration of their child's seizures without rescue medication was &lt;5 min in 35.7% of patients, 5-&lt;20 min in 42.6%, and ≥20 min in 21.7% (n = 258); with rescue medication seizure duration was &lt;5 min in 69.4% of patients, 5-&lt;20 min in 25.6%, and ≥20 min in 5.0%. Rescue medication use was significantly associated with average seizures lasting &lt;5 min (χ2 = 58.8; p &lt; 0.0001). At the time of their most recent PACS, 58.5-67.8% of children reportedly received rescue medication within 5 min of seizure onset, and 85.4-94.1% within 10 min.Conclusion: this study provides the first real-world data that rescue medications administered in the community reduce the duration of PACS in children with epilepsy. Study limitations including potential recall bias are acknowledged.</p

AMPA receptor GluA2 subunit defects are a cause of neurodevelopmental disorders

Neurodevelopmental disorders; AMPA; GluA2Trastorns del neurodesenvolupament; AMPA; GluA2Trastornos del neurodesarrollo; AMPA; GluA2AMPA receptors (AMPARs) are tetrameric ligand-gated channels made up of combinations of GluA1-4 subunits encoded by GRIA1-4 genes. GluA2 has an especially important role because, following post-transcriptional editing at the Q607 site, it renders heteromultimeric AMPARs Ca2+-impermeable, with a linear relationship between current and trans-membrane voltage. Here, we report heterozygous de novo GRIA2 mutations in 28 unrelated patients with intellectual disability (ID) and neurodevelopmental abnormalities including autism spectrum disorder (ASD), Rett syndrome-like features, and seizures or developmental epileptic encephalopathy (DEE). In functional expression studies, mutations lead to a decrease in agonist-evoked current mediated by mutant subunits compared to wild-type channels. When GluA2 subunits are co-expressed with GluA1, most GRIA2 mutations cause a decreased current amplitude and some also affect voltage rectification. Our results show that de-novo variants in GRIA2 can cause neurodevelopmental disorders, complementing evidence that other genetic causes of ID, ASD and DEE also disrupt glutamatergic synaptic transmission.Supported by the Wellcome Trust (WT093205MA and WT104033AIA), Medical Research Council (H.H. and D.M.K.), European Community’s Seventh Framework Programme (FP7/2007‐2013, under grant agreement No. 2012‐305121 to H.H.), Muscular Dystrophy Association (MDA), Muscular Dystrophy UK, The MSA Trust, Ataxia UK, The Sparkes Children’s Medical Research Charity, The Great Ormond Street Hospital Charity, Rosetrees Trust, Brain Research UK, The UK HSP Society, The European Union’s Horizon 2020 research and innovation programme Solve-RD project (No 779257), The Pakistan Council (Scholarship to HT), The National Natural Science Foundation of China (31671114, 81871079, 81330027, and 81525007 to H.G. and K.X.), the US National Institutes of Health (NIH grant R01MH101221 to E.E.E), the National Institute for Health Research (NIHR) University College London Hospitals (UCLH) and the Biomedical Research Centre (BRC