Automated High-Content Imaging in iPSC-derived Neuronal Progenitors

Induced pluripotent stem cells (iPSCs) have great potential as physiological disease models for human disorders where access to primary cells is difficult, such as neurons. In recent years, many protocols have been developed for the generation of iPSCs and the differentiation into specialised cell subtypes of interest. More recently, these models have been modified to allow large-scale phenotyping and high-content screening of small molecule compounds in iPSC-derived neuronal cells. Here, we describe the automated seeding of day 11 ventral midbrain progenitor cells into 96-well plates, administration of compounds, automated staining for immunofluorescence, the acquisition of images on a high-content screening platform and workflows for image analysis

New Perspectives in Dried Blood Spot Biomarkers for Lysosomal Storage Diseases

Dried blood spots (DBSs) biomarkers are convenient for monitoring for specific lysosomal storage diseases (LSDs), but they could have relevance for other LSDs. To determine the specificity and utility of glycosphingolipidoses biomarkers against other LSDs, we applied a multiplexed lipid liquid chromatography tandem mass spectrometry assay to a DBS cohort of healthy controls (n = 10) and Gaucher (n = 4), Fabry (n = 10), Pompe (n = 2), mucopolysaccharidosis types I–VI (n = 52), and Niemann–Pick disease type C (NPC) (n = 5) patients. We observed no complete disease specificity for any of the markers tested. However, comparison among the different LSDs highlighted new applications and perspectives of the existing biomarkers. We observed elevations in glucosylceramide isoforms in the NPC and Gaucher patients relative to the controls. In NPC, there was a greater proportion of C24 isoforms, giving a specificity of 96–97% for NPC, higher than 92% for the NPC biomarker N-palmitoyl-O-phosphocholineserine ratio to lyso-sphingomyelin. We also observed significantly elevated levels of lyso-dihexosylceramide in Gaucher and Fabry disease as well as elevated lyso-globotriaosylceramide (Lyso-Gb3) in Gaucher disease and the neuronopathic forms of Mucopolysaccharidoses. In conclusion, DBS glucosylceramide isoform profiling has increased the specificity for the detection of NPC, thereby improving diagnostic accuracy. Low levels of lyso-lipids can be observed in other LSDs, which may have implications in their disease pathogenesis

Niemann–Pick type C disease as proof-of-concept for intelligent biomarker panel selection in neurometabolic disorders

AIM: Using Niemann-Pick type C disease (NPC) as a paradigm, we aimed to improve biomarker discovery in patients with neurometabolic disorders. METHOD: Using a multiplexed liquid chromatography tandem mass spectrometry dried bloodspot assay, we developed a selective intelligent biomarker panel to monitor known biomarkers N-palmitoyl-O-phosphocholineserine and 3β,5α,6β-trihydroxy-cholanoyl-glycine as well as compounds predicted to be affected in NPC pathology. We applied this panel to a clinically relevant paediatric patient cohort (n = 75; 35 males, 40 females; mean age 7 years 6 months, range 4 days-19 years 8 months) presenting with neurodevelopmental and/or neurodegenerative pathology, similar to that observed in NPC. RESULTS: The panel had a far superior performance compared with individual biomarkers. Namely, NPC-related established biomarkers used individually had 91% to 97% specificity but the combined panel had 100% specificity. Moreover, multivariate analysis revealed long-chain isoforms of glucosylceramide were elevated and very specific for patients with NPC. INTERPRETATION: Despite advancements in next-generation sequencing and precision medicine, neurological non-enzymatic disorders remain difficult to diagnose and lack robust biomarkers or routine functional testing for genetic variants of unknown significance. Biomarker panels may have better diagnostic accuracy than individual biomarkers in neurometabolic disorders, hence they can facilitate more prompt disease identification and implementation of emerging targeted, disease-specific therapies

The Genetic Landscape of Complex Childhood-Onset Hyperkinetic Movement Disorders

Acord transformatiu CRUE-CSICThis work was supported by an NIHR Professorship (to M.A.K.). M.A.K. has received funding from the Sir Jules Thorn Award for Biomedical Research and Wellcome Trust. B.P.-D. was supported by Instituto de Salud Carlos III, PI 18/01319 and PI21/00248, and has received funding from Beca José Castillejos (CAS14/00328). K.J.P. was supported by an MRC Clinician-Scientist Fellowship (511015) and was supported by the Dystonia Medical Research Foundation and Fight for Sight. S.S.M. has received funding from the Winston Churchill Memorial trust and Cerebral Palsy Alliance.Background and Objective: The objective of this study was to better delineate the genetic landscape and key clinical characteristics of complex, early-onset, monogenic hyperkinetic movement disorders. Methods: Patients were recruited from 14 international centers. Participating clinicians completed standardized proformas capturing demographic, clinical, and genetic data. Two pediatric movement disorder experts reviewed available video footage, classifying hyperkinetic movements according to published criteria. Results: One hundred forty patients with pathogenic variants in 17 different genes (ADCY5, ATP1A3, DDC, DHPR, FOXG1, GCH1, GNAO1, KMT2B, MICU1, NKX2.1, PDE10A, PTPS, SGCE, SLC2A1, SLC6A3, SPR, and TH) were identified. In the majority, hyperkinetic movements were generalized (77%), with most patients (69%) manifesting combined motor semiologies. Parkinsonism-dystonia was characteristic of primary neurotransmitter disorders (DDC, DHPR, PTPS, SLC6A3, SPR, TH); chorea predominated in ADCY5-, ATP1A3-, FOXG1-, NKX2.1-, SLC2A1-, GNAO1-, and PDE10A-related disorders; and stereotypies were a prominent feature in FOXG1- and GNAO1-related disease. Those with generalized hyperkinetic movements had an earlier disease onset than those with focal/segmental distribution (2.5 ± 0.3 vs. 4.7 ± 0.7 years; P = 0.007). Patients with developmental delay also presented with hyperkinetic movements earlier than those with normal neurodevelopment (1.5 ± 2.9 vs. 4.7 ± 3.8 years; P < 0.001). Effective disease-specific therapies included dopaminergic agents for neurotransmitters disorders, ketogenic diet for glucose transporter deficiency, and deep brain stimulation for SGCE-, KMT2B-, and GNAO1-related hyperkinesia. Conclusions: This study highlights the complex phenotypes observed in children with genetic hyperkinetic movement disorders that can lead to diagnostic difficulty. We provide a comprehensive analysis of motor semiology to guide physicians in the genetic investigation of these patients, to facilitate early diagnosis, precision medicine treatments, and genetic counseling. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Clinical and molecular characterisation of KCNT1-related severe early onset epilepsy

Objective: To characterise the phenotypic spectrum, molecular genetic findings and functional consequences of pathogenic variants in early onset KCNT1-epilepsy. Methods: We identified a cohort of 31 patients with epilepsy of infancy with migrating focal seizures (EIMFS) and screened for variants in KCNT1 using direct Sanger sequencing, a multiple gene next generation sequencing panel and whole exome sequencing. Additional patients with non-EIMFS early onset epilepsy in whom we identified KCNT1 variants on local diagnostic multiple gene panel testing were also included. Where possible, we performed homology modelling to predict putative effects of variants on protein structure and function. We undertook electrophysiological assessment of mutant KCNT1 channels in a Xenopus oocyte model system. Results: We identified pathogenic variants in KCNT1 in 12 patients, four of which are novel. Most variants occurred de novo. Ten had a clinical diagnosis of EIMFS and the other two presented with early onset severe nocturnal frontal lobe seizures. Three patients had a trial of quinidine with good clinical response in one. Computational modelling analysis implicates abnormal pore function (F346L) and impaired tetramer formation (F502V) as putative disease mechanisms. All evaluated KCNT1 variants resulted in marked gain-of-function, with significantly increased channel amplitude and variable blockade by quinidine. Conclusions: Gain-of-function KCNT1 pathogenic variants cause a spectrum of severe focal epilepsies with onset in early infancy. Currently, genotype-phenotype correlations are unclear, though clinical outcome is poor for the majority of cases. Further elucidation of disease mechanisms may facilitate the development of targeted treatments, much needed for this pharmacoresistant genetic epilepsy

Mutations in the histone methyltransferase gene KMT2B cause complex early-onset dystonia.

Histone lysine methylation, mediated by mixed-lineage leukemia (MLL) proteins, is now known to be critical in the regulation of gene expression, genomic stability, cell cycle and nuclear architecture. Despite MLL proteins being postulated as essential for normal development, little is known about the specific functions of the different MLL lysine methyltransferases. Here we report heterozygous variants in the gene KMT2B (also known as MLL4) in 27 unrelated individuals with a complex progressive childhood-onset dystonia, often associated with a typical facial appearance and characteristic brain magnetic resonance imaging findings. Over time, the majority of affected individuals developed prominent cervical, cranial and laryngeal dystonia. Marked clinical benefit, including the restoration of independent ambulation in some cases, was observed following deep brain stimulation (DBS). These findings highlight a clinically recognizable and potentially treatable form of genetic dystonia, demonstrating the crucial role of KMT2B in the physiological control of voluntary movement.Funding for the project was provided by the Wellcome Trust for UK10K (WT091310) and DDD Study. The DDD study presents independent research commissioned by the Health Innovation Challenge Fund [grant number HICF-1009-003] - see www.ddduk.org/access.html for full acknowledgement. This work was supported in part by the Intramural Research Program of the National Human Genome Research Institute and the Common Fund, NIH Office of the Director. This work was supported in part by the German Ministry of Research and Education (grant nos. 01GS08160 and 01GS08167; German Mental Retardation Network) as part of the National Genome Research Network to A.R. and D.W. and by the Deutsche Forschungsgemeinschaft (AB393/2-2) to A.R. Brain expression data was provided by the UK Human Brain Expression Consortium (UKBEC), which comprises John A. Hardy, Mina Ryten, Michael Weale, Daniah Trabzuni, Adaikalavan Ramasamy, Colin Smith and Robert Walker, affiliated with UCL Institute of Neurology (J.H., M.R., D.T.), King’s College London (M.R., M.W., A.R.) and the University of Edinburgh (C.S., R.W.)

Investigation of Disease Mechanisms and Screening for Treatments in Betapropeller Protein-Associated Neurodegeneration (BPAN)

INTRODUCTION: BPAN is a monogenic form of neurodegeneration, associated with brain iron accumulation and early-onset parkinsonism. It is caused by mutations in WDR45, an X-linked gene with role in early autophagy. The mechanisms linking autophagy, iron load and neurodegeneration are poorly understood, while there are no effective treatments for BPAN. I aimed to address these issues by developing a patient-derived, induced pluripotent stem cell (iPSC)-based dopaminergic neuronal cell model of the disease. METHODS: 3 paediatric patient-derived iPSC lines, 2 age-matched controls and 2 ‘isogenic controls’ (generated via CRISPR/Cas9-mediated mutation correction in 2 BPAN lines) were differentiated into dopaminergic neurons using a 65-day protocol. High content imaging assays were developed for a drug screen, looking for small molecules that reverse patient specific cellular phenotypes. RESULTS: At Day 65 there is absence of WDR45 protein in patient lines. RNA sequencing reveals differential gene expression in 190 genes when comparing patients to controls. When plated on multi-well plates at low density, BPAN ventral midbrain progenitors (Day 11 of differentiation) exhibit defective autophagy, with fewer LC3 puncta per cell forming compared to controls. This assay was used to perform a drug screen using the FDA-approved Prestwick library (1,280 compounds) and a series of novel autophagy activators. Some compound hits significantly enhance autophagy in all tested lines and show promise for further development. CONCLUSION: I have used a patient-derived dopaminergic model of BPAN for disease modelling and also as a platform for high content imaging-based drug screening. My work contributes towards identifying novel, effective treatments for BPAN, and increases our understanding of the link between autophagy and neurodegeneration

Comparative Efficacy and Side Effect Profiles of Interventions for Pediatric Saliva Control:A Cohort Study

OBJECTIVE: To compare efficacy and side effect profile data on conservative, behavioral, pharmacological, and surgical treatments used for pediatric saliva control.STUDY DESIGN: A cohort study of children (n = 483) referred to a specialty Saliva Control service between May 2014 and November 2019 was performed, using quantitative data from pretreatment and post-treatment questionnaires (the Drooling Impact Scale [DIS], Drooling Rating Scale [DRS]) and recording of side effects. Overall, 483 children were included; treatment choices were based on published international guidelines.RESULTS: The greatest improvement was seen after intraglandular botulinum toxin A (BTX-A) injections (n = 207; 551 courses; mean DIS change, 34.7; 95% CI = 29.2-35.7) or duct transpositional surgery (n = 31; mean change in DIS, 29.0; 95% CI, 22.3-35.7). Oral anticholinergics were associated with good outcomes, with no significant statistical difference between glycopyrronium bromide (n = 150; mean DIS change, 21.5; 95% CI, 19.1-24.0) or trihexyphenidyl (n = 87; mean DIS change, 22.4; 95% CI, 18.9-25.8). Inhaled ipratropium bromide was not as efficacious (n = 80; mean DIS change, 11.1; 95% CI, 8.9-13.3). Oromotor programs were used in a selected group with reliable outcomes (n = 9; mean DIS change, 13.0). Side effects were consistent with previous studies. Overall, in cases of milder severity, enterally administered therapies provided a good first-line option. With more severe problems, BTX-A injections or saliva duct transpositional surgery were more effective and well tolerated.CONCLUSIONS: We describe a large, single-center pediatric saliva control cohort, providing direct comparison of the efficacy and side effect profiles for all available interventions and inform clinical practice for specialists when considering different options. BTX-A injections or saliva duct transpositional surgery seem to be more effective for saliva control that is more severe.</p

The expanding spectrum of movement disorders in genetic epilepsies

An ever-increasing number of neurogenetic conditions presenting with both epilepsy and atypical movements are now recognized. These disorders within the ‘genetic epilepsy-dyskinesia’ spectrum are clinically and genetically heterogeneous. Increased clinical awareness is therefore necessary for a rational diagnostic approach. Furthermore, careful interpretation of genetic results is key to establishing the correct diagnosis and initiating disease-specific management strategies in a timely fashion. In this review we describe the spectrum of movement disorders associated with genetically determined epilepsies. We also propose diagnostic strategies and putative pathogenic mechanisms causing these complex syndromes associated with both seizures and atypical motor control. What this paper adds: Implicated genes encode proteins with very diverse functions. Pathophysiological mechanisms by which epilepsy and movement disorder phenotypes manifest are often not clear. Early diagnosis of treatable disorders is essential and next generation sequencing may be required