A de novo CSDE1 variant causing neurodevelopmental delay, intellectual disability, neurologic and psychiatric symptoms in a child of consanguineous parents.

Funder: National Human Genome Research Institute; Id: http://dx.doi.org/10.13039/100000051Funder: Broad Institute; Id: http://dx.doi.org/10.13039/100013114Funder: Horizon 2020; Id: http://dx.doi.org/10.13039/100010661Funder: Muscular Dystrophy Canada; Id: http://dx.doi.org/10.13039/501100000223Funder: Evelyn Trust; Id: http://dx.doi.org/10.13039/501100004282Funder: European Regional Development Fund; Id: http://dx.doi.org/10.13039/501100008530CSDE1 encodes the cytoplasmic cold shock domain-containing protein E1 (CSDE1), which is highly conserved across species and functions as an RNA-binding protein involved in translationally coupled mRNA turnover. CSDE1 displays a bidirectional role: promoting and repressing the translation of RNAs but also increasing and decreasing the abundance of RNAs. Preclinical studies highlighted an involvement of CSDE1 in different forms of cancer. Moreover, CSDE1 is highly expressed in human embryonic stem cells and plays a role in neuronal migration and differentiation. A genome-wide association study suggested CSDE1 as a potential autism-spectrum disorder risk gene. A multicenter next generation sequencing approach unraveled likely causative heterozygous variants in CSDE1 in 18 patients, identifying a new autism spectrum disorder-related syndrome consisting of autism, intellectual disability, and neurodevelopmental delay. Since then, no further patients with CSDE1 variants have been reported in the literature. Here, we report a 9.5-year-old girl from a consanguineous family of Turkish origin suffering from profound delayed speech and motor development, moderate intellectual disability, neurologic and psychiatric symptoms as well as hypoplasia of corpus callosum and mildly reduced brain volume on brain magnetic resonance imaging associated with a recurrent de novo mutation in CSDE1 (c.367C > T; p.R123*) expanding the phenotypical spectrum associated with pathogenic CSDE1 variants

Homozygous WASHC4 variant in two sisters causes a syndromic phenotype defined by dysmorphisms, intellectual disability, profound developmental disorder, and skeletal muscle involvement.

Funder: European Regional Development Fund; Id: http://dx.doi.org/10.13039/501100008530Recessive variants in WASHC4 are linked to intellectual disability complicated by poor language skills, short stature, and dysmorphic features. The protein encoded by WASHC4 is part of the Wiskott-Aldrich syndrome protein and SCAR homolog family, co-localizes with actin in cells, and promotes Arp2/3-dependent actin polymerization in vitro. Functional studies in a zebrafish model suggested that WASHC4 knockdown may also affect skeletal muscles by perturbing protein clearance. However, skeletal muscle involvement has not been reported so far in patients, and precise biochemical studies allowing a deeper understanding of the molecular etiology of the disease are still lacking. Here, we report two siblings with a homozygous WASHC4 variant expanding the clinical spectrum of the disease and provide a phenotypical comparison with cases reported in the literature. Proteomic profiling of fibroblasts of the WASHC4-deficient patient revealed dysregulation of proteins relevant for the maintenance of the neuromuscular axis. Immunostaining on a muscle biopsy derived from the same patient confirmed dysregulation of proteins relevant for proper muscle function, thus highlighting an affliction of muscle cells upon loss of functional WASHC4. The results of histological and coherent anti-Stokes Raman scattering microscopic studies support the concept of a functional role of the WASHC4 protein in humans by altering protein processing and clearance. The proteomic analysis confirmed key molecular players in vitro and highlighted, for the first time, the involvement of skeletal muscle in patients. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland

Phenotype and genetic analysis of data collected within the first year of NeuroDev

Genetic association studies have made significant contributions to our understanding of the etiology of neurodevelopmental disorders (NDDs). However, these studies rarely focused on the African continent. The NeuroDev Project aims to address this diversity gap through detailed phenotypic and genetic characterization of children with NDDs from Kenya and South Africa. We present results from NeuroDev’s first year of data collection, including phenotype data from 206 cases and clinical genetic analyses of 99 parent-child trios. Most cases met criteria for global developmental delay/intellectual disability (GDD/ID, 80.3%). Approximately half of the children with GDD/ID also met criteria for autism. Analysis of exome-sequencing data identified a pathogenic or likely pathogenic variant in 13 (17%) of the 75 cases from South Africa and 9 (38%) of the 24 cases from Kenya. Data from the trio pilot are publicly available, and the NeuroDev Project will continue to develop resources for the global genetics community

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

Pathogenic variants in SMARCA1 cause an X-linked neurodevelopmental disorder modulated by NURF complex composition

Pathogenic variants in ATP-dependent chromatin remodeling proteins are a recurrent cause of neurodevelopmental disorders (NDDs). The NURF complex consists of BPTF and either the SNF2H ( SMARCA5) or SNF2L ( SMARCA1) ISWI-chromatin remodeling enzyme. Pathogenic variants in BPTF and SMARCA5 were previously implicated in NDDs. Here, we describe 40 individuals from 30 families with de novo or maternally inherited pathogenic variants in SMARCA1. This novel NDD was associated with mild to severe ID/DD, delayed or regressive speech development, and some recurrent facial dysmorphisms. Individuals carrying SMARCA1 loss-of-function variants exhibited a mild genome-wide DNA methylation profile and a high penetrance of macrocephaly. Genetic dissection of the NURF complex using Smarca1, Smarca5, and Bptfsingle and double mouse knockouts revealed the importance of NURF composition and dosage for proper forebrain development. Finally, we propose that genetic alterations affecting different NURF components result in a NDD with a broad clinical spectrum

Ehlers-Danlos/myopathy overlap syndrome caused by a large de novo deletion in COL12A1

Autosomal dominant and recessive mutations in COL12A1 cause the Ehlers-Danlos/myopathy overlap syndrome. Here, we describe a boy with fetal hypokinesia, severe neonatal weakness, striking hyperlaxity, high arched palate, retrognathia, club feet, and pectus excavatum. His motor development was initially delayed but muscle strength improved with time while hyperlaxity remained very severe causing recurrent joint dislocations. Using trio exome sequencing and a copy number variation (CNV) analysis tool, we identified an in-frame de novo heterozygous deletion of the exons 45 to 54 in the COL12A1 gene. Collagen XII immunostaining on cultured skin fibroblasts demonstrated intracellular retention of collagen XII, supporting the pathogenicity of the deletion. The phenotype of our patient is slightly more severe than other cases with dominantly acting mutations, notably with the presence of fetal hypokinesia. This case highlights the importance of CNVs analysis in the COL12A1 gene in patients with a phenotype suggesting Ehlers-Danlos/myopathy overlap syndrome

Unique Capabilities of Genome Sequencing for Rare Disease Diagnosis

BackgroundCausal variants underlying rare disorders may remain elusive even after expansive gene panels or exome sequencing (ES). Clinicians and researchers may then turn to genome sequencing (GS), though the added value of this technique and its optimal use remain poorly defined. We therefore investigated the advantages of GS within a phenotypically diverse cohort.MethodsGS was performed for 744 individuals with rare disease who were genetically undiagnosed. Analysis included review of single nucleotide, indel, structural, and mitochondrial variants.ResultsWe successfully solved 218/744 (29.3%) cases using GS, with most solves involving established disease genes (157/218, 72.0%). Of all solved cases, 148 (67.9%) had previously had non-diagnostic ES. We systematically evaluated the 218 causal variants for features requiring GS to identify and 61/218 (28.0%) met these criteria, representing 8.2% of the entire cohort. These included small structural variants (13), copy neutral inversions and complex rearrangements (8), tandem repeat expansions (6), deep intronic variants (15), and coding variants that may be more easily found using GS related to uniformity of coverage (19).ConclusionWe describe the diagnostic yield of GS in a large and diverse cohort, illustrating several types of pathogenic variation eluding ES or other techniques. Our results reveal a higher diagnostic yield of GS, supporting the utility of a genome-first approach, with consideration of GS as a secondary or tertiary test when higher-resolution structural variant analysis is needed or there is a strong clinical suspicion for a condition and prior targeted genetic testing has been negative

Digenic inheritance involving a muscle-specific protein kinase and the giant titin protein causes a skeletal muscle myopathy.

Acknowledgements: We acknowledge H. Luque, L. Phillips, J. Casement, O. Magnuson, D. Nguyen and Y. Hu for technical support; R. García-Tercero and C. Díaz for sample collection; E. Zorio, M.E. Leach, D. Bharucha-Goebel, J. Dastgir and C. Konersman for clinical expertise and M. Gautel for helpful advice. We also thank CureCMD for their help in patient recruitment and the patients for donating their samples. The research leading to these results has received funding from the European Community’s Seventh Framework Program (FP7/2007-2013; 2012-305121) ‘Integrated European—omics research project for diagnosis and therapy in rare neuromuscular and neurodegenerative diseases (NEUROMICS)’ (to A. Töpf, V.S., I.T.Z. and F.M.); the European Union’s Horizon 2020 research and innovation program (Solve-RD project; 779257 to A. Töpf); Muscular Dystrophy UK and Muscular Dystrophy Association US (mda577346 to F.M.); Päulon Säätiö (to M. Savarese); Academy of Finland, Sigrid Juselius Foundation (to B.U.); core funding to the Sanger Institute by the Wellcome Trust (098051 and 206194 to E.M.B.-N., J.P. and N.W.); EURO-NMD and Fundación Gemio (to J.J.V., N.M. and P.M.); Intramural Research Grant (2-5, 29-4) for Neurological and Psychiatric Disorders of NCNP and AMED (JP20ek0109490h0001 to I.N.); Inserm, CNRS, University of Strasbourg, Labex INRT (ANR-10-LABX-0030 and ANR-10-IDEX-0002-02), France Génomique (ANR-10-INBS-09) and Fondation Maladies Rares for the ‘Myocapture’ sequencing project, AFM-Téléthon (22734), the European Joint program (EJPRD2019-126 IDOLS-G and ANR-19-RAR4-0002 to J.L., X.L. and V.B.); Intramural funds from the NIH National Institute of Neurological Disorders and Stroke (to C.G.B.); the Dutch Princess Beatrix Muscle Fund and the Dutch Spieren voor Spieren Muscle fund (to C.E.E.); PI16/00316 supported by the Instituto de Salud Carlos III (ISCIII), Madrid and the Generalitat Valenciana (grant PROMETEO/2019/075 to N.M.); Australian NHMRC Neil Hamilton Fairley Early Career Research Fellowship (GNT1090428 to E.C.O.); Starship Foundation A+7340 (to G.L.O.); Early Career Award from the Thrasher Research Fund (to S.S.); U54 HD090255 from the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (to A.H.B.); Wellcome Center for Mitochondrial Research (203105/Z/16/Z), the Mitochondrial Disease Patient Cohort (UK; G0800674), the Medical Research Council International Center for Genomic Medicine in Neuromuscular Disease (MR/S005021/1), the Medical Research Council (MR/W019027/1), the Lily Foundation, Mito Foundation, the Pathological Society, the UK NIHR Biomedical Research Center for Ageing and Age-related Disease award to the Newcastle upon Tyne Foundation Hospitals NHS Trust and the UK NHS Highly Specialized Service for Rare Mitochondrial Disorders of Adults and Children (to R.W.T.). MYO–SEQ was funded by Sanofi Genzyme, Ultragenyx, LGMD2I Research Fund, Samantha J Brazzo Foundation, LGMD2D Foundation, Kurt+Peter Foundation, Muscular Dystrophy UK and Coalition to Cure Calpain 3. Sequencing and analysis for relevant families (Supplementary Note) were provided 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 and the National Heart, Lung and Blood Institute under grant UM1 HG008900 and the National Human Genome Research Institute under grants U01HG0011755 and R01 HG009141. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. DNA samples for NeurOmics and MYO–SEQ were provided by the John Walton Muscular Dystrophy Research Center Biobank. This facility is supported by the NIHR Newcastle Biomedical Research Center. Newcastle University’s Electron Microscopy Research Services and equipment Hitachi HT7800 120 kV TEM microscope are funded by BBSRC grant reference BB/R013942/1.Funder: Genzyme (Genzyme Corporation); doi: https://doi.org/10.13039/100004329Funder: Ultragenyx Pharmaceutical (Ultragenyx Pharmaceutical Inc.); doi: https://doi.org/10.13039/100013220Funder: EC | EC Seventh Framework Programm | FP7 Ideas: European Research Council (FP7-IDEAS-ERC - Specific Programme: "Ideas" Implementing the Seventh Framework Programme of the European Community for Research, Technological Development and Demonstration Activities (2007 to 2013)); doi: https://doi.org/10.13039/100011199; Grant(s): 2012-305121In digenic inheritance, pathogenic variants in two genes must be inherited together to cause disease. Only very few examples of digenic inheritance have been described in the neuromuscular disease field. Here we show that predicted deleterious variants in SRPK3, encoding the X-linked serine/argenine protein kinase 3, lead to a progressive early onset skeletal muscle myopathy only when in combination with heterozygous variants in the TTN gene. The co-occurrence of predicted deleterious SRPK3/TTN variants was not seen among 76,702 healthy male individuals, and statistical modeling strongly supported digenic inheritance as the best-fitting model. Furthermore, double-mutant zebrafish (srpk3-/-; ttn.1+/-) replicated the myopathic phenotype and showed myofibrillar disorganization. Transcriptome data suggest that the interaction of srpk3 and ttn.1 in zebrafish occurs at a post-transcriptional level. We propose that digenic inheritance of deleterious changes impacting both the protein kinase SRPK3 and the giant muscle protein titin causes a skeletal myopathy and might serve as a model for other genetic diseases