Spinocerebellar ataxia: an update

SCA44- and SCAR13-associated GRM1 mutations affect metabotropic glutamate receptor 1 function through distinct mechanisms

BACKGROUND AND PURPOSE

Metabotropic glutamate receptor 1 (mGlu1) is a promising therapeutic target for neurodegenerative CNS disorders including spinocerebellar ataxias (SCAs). Clinical reports have identified naturally-occurring mGlu1 mutations in rare SCA subtypes and linked symptoms to mGlu1 mutations. However, how mutations alter mGlu1 function remains unknown, as does amenability of receptor function to pharmacological rescue. Here, we explored SCA-associated mutation effects on mGlu1 cell surface expression, canonical signal transduction and allosteric ligand pharmacology.

EXPERIMENTAL APPROACH

Orthosteric agonists, positive allosteric modulators (PAMs) and negative allosteric modulators (NAMs) were assessed at two functional endpoints (iCa2+ mobilisation and inositol 1-phosphate [IP1] accumulation) in FlpIn Trex HEK293A cell lines expressing five mutant mGlu1 subtypes. Key pharmacological parameters including ligand potency, affinity and cooperativity were derived using operational models of agonism and allostery.

KEY RESULTS

mGlu1 mutants exhibited differential impacts on mGlu1 expression, with a C-terminus truncation significantly reducing surface expression. Mutations differentially influenced orthosteric ligand affinity, efficacy and functional cooperativity between allosteric and orthosteric ligands. Loss-of-function mutations L454F and N885del reduced orthosteric affinity and efficacy, respectively. A gain-of-function Y792C mutant mGlu1 displayed enhanced constitutive activity in IP1 assays, which manifested as reduced orthosteric agonist activity. The mGlu1 PAMs restored glutamate potency in iCa2+ mobilisation for loss-of-function mutations and mGlu1 NAMs displayed enhanced inverse agonist activity at Y792C relative to wild-type mGlu1.

CONCLUSION AND IMPLICATIONS

Collectively, these data highlight distinct mechanisms by which mGlu1 mutations affect receptor function and show allosteric modulators may present a therapeutic strategy to restore aberrant mGlu1 function in rare SCA subtypes.

The autophagy paradox: A new hypothesis in neurodegenerative disorders

A recent study showed that while autophagy is usually tied to protein and organelle turnover, it can also play dual roles in neurodegenerative diseases. Traditionally, autophagy was seen as protective since it removes damaged proteins and organelles. but new data suggests autophagy can sometimes promote neuron death. and This review tackles autophagy's seemingly contradictory effects in neurodegeneration, or the "autophagy paradox. " It offers a framework for understanding autophagy in neurodegenerative research and the cellular processes involved. In short, our data uncovers a harmful autophagy role in certain situations, conflicting the view that it's always beneficial. We describe the distinct, disease-specific autophagy pathways functioning in various neurodegenerative diseases. Part two concerns potential therapeutic implications of manipulating autophagy and current strategies targeting the autophagic system, suggesting interesting areas for future research into tailored modulators. This could eventually enable activating or controlling specific autophagy pathways and aid in developing more effective treatments. Researchers believe more molecular-level research is needed so patient-tailored autophagy-modulating therapeutics can be developed given this dilemma. Moreover, research must translate faster into effective neurodegenerative disease treatment options. This article aims to provide a wholly new perspective on autophagy's classically described role in these severe diseases, challenging current dogma and opening new therapeutic avenue options.

Spinocerebellar Ataxia in Brazil: A Comprehensive Genotype - Phenotype Analysis

Spinocerebellar ataxias (SCAs) are a diverse group of hereditary neurodegenerative disorders characterized by progressive degeneration of the cerebellum and other parts of the nervous system. In this study, we examined the genotype‒phenotype correlations in SCAs within the Brazilian population by leveraging a comprehensive dataset of 763 individuals from SARAH Network of Rehabilitation Hospitals. Using a retrospective, cross-sectional, observational, multicentric approach, we analysed medical records and conducted standardized molecular testing to explore epidemiological characteristics, clinical manifestations, and genetic profiles of SCAs in Brazil. Our findings revealed the predominance of SCA3, followed by SCA7 and SCA2, which aligns with global trends and reflects the specific genetic landscape of Brazil. A significant inverse relationship between the age of symptom onset and CAG repeat length in the mutated allele was observed across SCAs 2, 3, and 7. This study also highlights a trend towards paternal inheritance in SCA2 and details the distribution of CAG repeat expansions, which correlates larger expansions with earlier onset and specific symptomatology. This extensive analysis underscores the critical importance of genetic testing in the diagnosis and management of SCAs and enlightens the intricate genotype‒phenotype interplay within a genetically diverse population. Despite certain limitations, such as potential selection bias and the retrospective nature of the study, our research provides invaluable insights into the prevalence, genetic underpinnings, and clinical variability of SCAs in Brazil. We suggest a broader demographic scope and investigations into nonmotor symptoms in future studies to obtain a more comprehensive understanding of SCAs.

CACNA1G Causes Dominantly Inherited Myoclonus-Ataxia with Intellectual Disability: A Case Report

Spinocerebellar ataxias (SCAs) are characterized by substantial phenotypic variability. Among them, SCA42 is a rare non-expansion entity presenting with slowly progressive cerebellar syndrome but whose clinical spectrum may be also wider. A 53-year-old male presented with progressive myoclonus-ataxia and intellectual disability. Genetic screening revealed a novel c.3835G > A (p. Asp1279Asn) variant in the CACNA1G gene. SCA42 is a rare non-expansion SCA caused by mutations in CACNA1G on chromosome 17q21, encoding the Ca(V)3.1, a low-threshold voltage-gated T-type calcium channel. The novel variant we identified is potentially involved in channel activity. This case expands the knowledge regarding CACNA1G-associated phenotype and highlights the importance of genetic screening in myoclonus-ataxia disorders.

Large-scale evidence for the validity of remote MoCA administration among people with cerebellar ataxia

Objective: For over half a century, studies of rare diseases using in-person cognitive tools have faced challenges, such as long study periods and small sample sizes (e.g. n = 10). The Montreal Cognitive Assessment (MoCA) was widely employed to assess mild cognitive impairment (MCI). We aimed to validate a modified online version of the MoCA in a large sample of a rare disease (population prevalence < .01%). Method: First, we analyzed 20 previous findings (n = 1,377), comparing the MoCA scores between large groups of neurotypically healthy (NH; n = 837) and cerebellar ataxia (CA; n = 540), where studies were conducted in-person. Second, we administered the MoCA in-person to a group of NH (n = 41) and a large group of CA (n = 103). Third, we administered a video conferencing version of the MoCA to NH (n = 38) and a large group of CA (n = 83). Results: We observed no performance differences between online and in-person MoCA administration in the NH and CA groups (p > .05, η2 = 0.001), supporting reliability. Additionally, our online CA group had lower MoCA scores than the NH group (p < .001, Hedges' g = 0.68). This result is consistent with previous studies, as demonstrated by our forest plot across 20 previous in-person findings, supporting construct validity. Conclusion: The results indicate that an online screening tool is valid in a large sample of individuals with CA. Online testing is not only time and cost-effective, but facilitates disease management and monitoring, ultimately enabling early detection of MCI.

Hormonal orchestra: mastering mitochondria's role in health and disease

Mitochondria is a subcellular organelle involved in the pathogenesis of cellular stress, immune responses, differentiation, metabolic disorders, aging, and death by regulating process of fission, fusion, mitophagy, and transport. However, an increased interest in mitochondria as powerhouse for ATP production, the mechanisms of mitochondria-mediated cellular dysfunction in response to hormonal interaction remains unknown. Mitochondrial matrix contains chaperones and proteases that regulate intrinsic apoptosis pathway through pro-apoptotic Bcl-2 family's proteins Bax/Bak, and Cyt C release, and induces caspase-dependent and independent cells death. Energy and growth regulators such as thyroid hormones have profound effect on mitochondrial inner membrane protein and lipid compositions, ATP production by regulating oxidative phosphorylation system. Mitochondria contain cholesterol side-chain cleavage enzyme, P450scc, ferredoxin, and ferredoxin reductase providing an essential site for steroid hormones biosynthesis. In line with this, neurohormones such as oxytocin, vasopressin, and melatonin are correlated with mitochondrial integrity, displaying therapeutic implications for inflammatory and immune responses. Melatonin's also displayed protective role against oxidative stress and mitochondrial synthesis of ROS, suggesting a defense mechanism against aging-related diseases. An imbalance in mitochondrial bioenergetics can cause neurodegenerative disorders, cardiovascular diseases, and cancers. Hormone-induced PGC-1α stimulates mitochondrial biogenesis via activation of NRF1 and NRF2, which in turn triggers mtTFA in brown adipose and cardiac myocytes. Mitochondria can be transferred through cells merging, exosome-mediated transfer, and tunneling through nanotubes. By delineating the underlying molecular mechanism of hormonal mitochondrial interaction, this study reviews the dynamics mechanisms of mitochondria and its effects on cellular level, health, diseases, and therapeutic strategies targeting mitochondrial diseases.

Investigation of Spinocerebellar Ataxia (SCA) Disease in Iranian Patients and Accurate Trinucleotide Repeat Detection in the SCA3 by TP-PCR Method

SCA (spinocerebellar ataxia) which is autosomal dominantly transferred is a subset of inherited cerebellar ataxia. These progressive neurological diseases have clinical features of ataxia and are derived from the destruction of the cerebellum. These diseases can also affect other areas, including the brainstem. Frequent proliferation of CAG nucleotides can encode polyglutamine and, as a result, produce the toxic polyglutamine (poly Q) protein that leads to many types of SCAs. They are categorized based on specific genetic mutations. The main symptoms of SCA, gait ataxia and incoordination, nystagmus, vision problems, and dysarthria, can be mentioned. In this study, 31 Iranians who were suspected of SCA disease were clinically diagnosed from November 2019 to September 2021. For these 31 patients suspected of spinocerebellar ataxia, PCR was performed, and the analysis was based on vertical electrophoresis. For SCA3 patients, the TP-PCR technique was carried out and evaluated by capillary electrophoresis. For all 31 patients, PCR function was successful according to the results attained by conventional PCR. The number of three nucleotide replications was within the normal range for 22 people, and nine patients were reported. Studies showed that three people suspected of SCA were infected with SCA3 according to the TP-PCR technique, and this was while seven people were diagnosed with SCA3 using the PCR method. As the purpose of this test is to provide a more accurate diagnostic method and prenatal diagnosis of this disease, the TP-PCR method proved to be more suitable when applied for the diagnosis of abnormal trinucleotides CAG in spinocerebellar ataxia type 3.

The Phenotypic Spectrum of Spinocerebellar Ataxia Type 19 in a Series of Latin American Patients

Spinocerebellar ataxia 19 (SCA19) represents a rare autosomal dominant genetic disorder resulting in progressive ataxia and cerebellar atrophy. SCA19 is caused by variants in the KCND3 gene, which encodes a voltage-gated potassium channel subunit essential for cerebellar Purkinje cell function. We describe six cases from Chile and Mexico, representing the largest report on SCA19 in Latin America. These cases encompass a range of clinical presentations, highlighting the phenotypic variability within SCA19 from an early-onset, severe disease to a late-onset, slowly progressive condition with normal lifespan. While some patients present with pure ataxia, others also show cognitive impairment, dystonia, and other neurological symptoms. The correlations between specific KCND3 variants and phenotypic outcomes are complex and warrant further investigation. As the genomic landscape of spinocerebellar ataxias evolves, comprehensive genetic testing is becoming pivotal in improving diagnostic accuracy. This study contributes to a better understanding of the clinical spectrum of SCA19, laying the groundwork for further genotype-phenotype correlations and functional studies to elucidate the underlying pathophysiology.

Video-Based Kinematic Analysis of Movement Quality in a Phase 3 Clinical Trial of Troriluzole in Adults with Spinocerebellar Ataxia: A Post Hoc Analysis

INTRODUCTION

Traditional methods for assessing movement quality rely on subjective standardized scales and clinical expertise. This limitation creates challenges for assessing patients with spinocerebellar ataxia (SCA), in whom changes in mobility can be subtle and varied. We hypothesized that a machine learning analytic system might complement traditional clinician-rated measures of gait. Our objective was to use a video-based assessment of gait dispersion to compare the effects of troriluzole with placebo on gait quality in adults with SCA.

METHODS

Participants with SCA underwent gait assessment in a phase 3, double-blind, placebo-controlled trial of troriluzole (NCT03701399). Videos were processed through a deep learning pose extraction algorithm, followed by the estimation of a novel gait stability measure, the Pose Dispersion Index, quantifying the frame-by-frame symmetry, balance, and stability during natural and tandem walk tasks. The effects of troriluzole treatment were assessed in mixed linear models, participant-level grouping, and treatment group-by-visit week interaction adjusted for age, sex, baseline modified Functional Scale for the Assessment and Rating of Ataxia (f-SARA), and time since diagnosis.

RESULTS

From 218 randomized participants, 67 and 56 participants had interpretable videos of a tandem and natural walk attempt, respectively. At Week 48, individuals assigned to troriluzole exhibited significant (p = 0.010) improvement in tandem walk Pose Dispersion Index versus placebo {adjusted interaction coefficient: 0.584 [95% confidence interval (CI) 0.137 to 1.031]}. A similar, nonsignificant trend was observed in the natural walk assessment [coefficient: 1.198 (95% CI - 1.067 to 3.462)]. Further, lower baseline Pose Dispersion Index during the natural walk was significantly (p = 0.041) associated with a higher risk of subsequent falls [adjusted Poisson coefficient: - 0.356 [95% CI - 0.697 to - 0.014)].

CONCLUSION

Using this novel approach, troriluzole-treated subjects demonstrated improvement in gait as compared to placebo for the tandem walk. Machine learning applied to video-captured gait parameters can complement clinician-reported motor assessment in adults with SCA. The Pose Dispersion Index may enhance assessment in future research. TRIAL REGISTRATION-CLINICALTRIALS.

GOV IDENTIFIER

NCT03701399.

Circadian rhythm alterations affecting the pathology of neurodegenerative diseases

The circadian rhythm is a nearly 24-h oscillation found in various physiological processes in the human brain and body that is regulated by environmental and genetic factors. It is responsible for maintaining body homeostasis and it is critical for essential functions, such as metabolic regulation and memory consolidation. Dysregulation in the circadian rhythm can negatively impact human health, resulting in cardiovascular and metabolic diseases, psychiatric disorders, and premature death. Emerging evidence points to a relationship between the dysregulation circadian rhythm and neurodegenerative diseases, suggesting that the alterations in circadian function might play crucial roles in the pathogenesis and progression of neurodegenerative diseases. Better understanding this association is of paramount importance to expand the knowledge on the pathophysiology of neurodegenerative diseases, as well as, to provide potential targets for the development of new interventions based on the dysregulation of circadian rhythm. Here we review the latest findings on dysregulation of circadian rhythm alterations in Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, spinocerebellar ataxia and multiple-system atrophy, focusing on research published in the last 3 years.

Progression of Retinal Ganglion Cell and Nerve Fiber Layer Loss in Spinocerebellar Ataxia 3 Patients

Spectral domain optical coherence tomography (SD-OCT) allows noninvasive measurements of retinal neuron layers. Here, we evaluate the relationship between clinical features and anatomical SD-OCT measurements in patients with spinocerebellar ataxia type 3 (SCA3) and how they change with time. A retrospective review was conducted on SCA3 patients. Clinical variables such as disease duration, number of CAG repeats, and the Scale for the Assessment and Rating of Ataxia (SARA) score were correlated with SD-OCT measurements, including retinal nerve fiber layer (RNFL) thickness, ganglion cell complex (GCC) thickness, macular volume (MV), and central macular thickness (CMT). Seventeen SCA3 patients with an average follow-up of 44.9 months were recruited. Clinical features with significant baseline correlations with SD-OCT measurements included disease duration (CMT r =  - 0.590; GCC r =  - 0.585), SARA score (CMT r =  - 0.560; RNFL r =  - 0.390), and number of CAG repeats (MV r =  - 0.552; RNFL r =  - 0.503; GCC r =  - 0.493). The annual rate of change of the SARA score during follow-up was associated with that of both the MV (r =  - 0.494; p = 0.005) and GCC thickness (r =  - 0.454; p = 0.012). High disability (stages 2 and 3) was independently inversely associated with the annual change in MV (ß coefficient - 17.09; p = 0.025). This study provides evidence of an association between clinical features and objective anatomical measurements obtained by SD-OCT in SCA3 patients. MV and GCC thickness could serve as potential biomarkers of disease severity, as their rates of decrease seem to be related to a worsening in the SARA score. These findings highlight the potential of SD-OCT as a noninvasive tool for assessing disease severity and progression in SCA3 patients.

Cerebellar Direct Current Stimulation Reveals the Causal Role of the Cerebellum in Temporal Prediction

Temporal prediction (TP) influences our perception and cognition. The cerebellum could mediate this multi-level ability in a context-dependent manner. We tested whether a modulation of the cerebellar neural activity, induced by transcranial Direct Current Stimulation (tDCS), changed the TP ability according to the temporal features of the context and the duration of target interval. Fifteen healthy participants received anodal, cathodal, and sham tDCS (15 min × 2 mA intensity) over the right cerebellar hemisphere during a TP task. We recorded reaction times (RTs) to a target during the task in two contextual conditions of temporal anticipation: rhythmic (i.e., interstimulus intervals (ISIs) were constant) and single-interval condition (i.e., the estimation of the timing of the target was based on the prior exposure of the train of stimuli). Two ISIs durations were explored: 600 ms (short trials) and 900 ms (long trials). Cathodal tDCS improved the performance during the TP task (shorter RTs) specifically in the rhythmic condition only for the short trials and in the single-interval condition only for the long trials. Our results suggest that the inhibition of cerebellar activity induced a different improvement in the TP ability according to the temporal features of the context. In the rhythmic context, the cerebellum could integrate the temporal estimation with the anticipatory motor responses critically for the short target interval. In the single-interval context, for the long trials, the cerebellum could play a main role in integrating representation of time interval in memory with the elapsed time providing an accurate temporal prediction.

Nilotinib treatment outcomes in autosomal dominant spinocerebellar ataxia over one year

We evaluated the efficacy and safety of 1-year treatment with nilotinib (Tasigna®) in patients with autosomal dominant spinocerebellar ataxia (ADSCA) and the factors associated with responsiveness. From an institutional cohort, patients with ADSCA who completed a 1-year treatment with nilotinib (150-300 mg/day) were included. Ataxia severity was assessed using the Scale for the Rating and Assessment of Ataxia (SARA), scores at baseline and 1, 3, 6, and 12 months. A subject was categorized 'responsive' when the SARA score reduction at 12 M was > 0. Pretreatment serum proteomic analysis included subjects with the highest (n = 5) and lowest (n = 5) SARA score change at 12 months and five non-ataxia controls. Thirty-two subjects (18 [56.2%] females, median age 42 [30-49.5] years) were included. Although SARA score at 12 M did not significantly improve in overall population, 20 (62.5%) subjects were categorized as responsive. Serum proteomic analysis identified 4 differentially expressed proteins, leucine-rich alpha-2-glycoprotein (LRG1), vitamin-D binding protein (DBP), and C4b-binding protein (C4BP) beta and alpha chain, which are involved in the autophagy process. This preliminary data suggests that nilotinib might improve ataxia severity in some patients with ADSCA. Serum protein markers might be a clue to predict the response to nilotinib.Trial Registration Information: Effect of Nilotinib in Cerebellar Ataxia Patients (NCT03932669, date of submission 01/05/2019).

In Silico Prediction of Potential Inhibitors for Targeting RNA CAG Repeats via Molecular Docking and Dynamics Simulation: A Drug Discovery Approach

Spinocerebellar ataxia (SCA) is a rare neurological illness inherited dominantly that causes severe impairment and premature mortality. While each rare disease may affect individuals infrequently, collectively they pose a significant healthcare challenge. It is mainly carried out due to the expansion of RNA triplet (CAG) repeats, although missense or point mutations can also be induced. Unfortunately, there is no cure; only symptomatic treatments are available. To date, SCA has about 48 subtypes, the most common of these being SCA 1, 2, 3, 6, 7, 12, and 17 having CAG repeats. Using molecular docking and molecular dynamics (MD) simulation, this study seeks to investigate effective natural herbal neuroprotective compounds against CAG repeats, which are therapeutically significant in treating SCA. Initially, virtual screening followed by molecular docking was used to estimate the binding affinity of neuroprotective natural compounds toward CAG repeats. The compound with the highest binding affinity, somniferine, was then chosen for MD simulation. The structural stability, interaction mechanism, and conformational dynamics of CAG repeats and somniferine were investigated via MD simulation. The MD study revealed that during the simulation period, the interaction between CAG repeats and somniferine stabilizes and results in fewer conformational variations. This in silico study suggests that Somniferine can be used as a therapeutic medication against RNA CAG repeats in SCA.

Practical recommendations for the clinical evaluation of patients with hereditary ataxia and hereditary spastic paraplegia

Hereditary ataxia (HA) and hereditary spastic paraplegia (HSP) are rare diseases; as such, they are rarely managed in general neurology consultations. We present a set of brief, practical recommendations for the diagnosis and management of these patients, as well as a standardised procedure for comprehensive evaluation of disability. We provide definitions for HA and "HA plus," and "pure" and "complicated" HSP; describe the clinical assessment of these patients, indicating the main complementary tests and clinical scales for physical and psychological assessment of the patients; and summarise the available treatments. These recommendations are intended to facilitate daily neurological practice and to unify clinical criteria and disability assessment protocols for patients with HA and HSP.

Tremor in Spinocerebellar Ataxia: A Scoping Review

Background

Spinocerebellar ataxia (SCA) denotes an expanding list of autosomal dominant cerebellar ataxias. Although tremor is an important aspect of the clinical spectrum of the SCAs, its prevalence, phenomenology, and pathophysiology are unknown.

Objectives

This review aims to describe the various types of tremors seen in the different SCAs, with a discussion on the pathophysiology of the tremors, and the possible treatment modalities.

Methods

The authors conducted a literature search on PubMed using search terms including tremor and the various SCAs. Relevant articles were included in the review after excluding duplicate publications.

Results

While action (postural and intention) tremors are most frequently associated with SCA, rest and other rare tremors have also been documented. The prevalence and types of tremors vary among the different SCAs. SCA12, common in certain ethnic populations, presents a unique situation, where the tremor is typically the principal manifestation. Clinical manifestations of SCAs may be confused with essential tremor or Parkinson's disease. The pathophysiology of tremors in SCAs predominantly involves the cerebellum and its networks, especially the cerebello-thalamo-cortical circuit. Additionally, connections with the basal ganglia, and striatal dopaminergic dysfunction may have a role. Medical management of tremor is usually guided by the phenomenology and associated clinical features. Deep brain stimulation surgery may be helpful in treatment-resistant tremors.

Conclusions

Tremor is an elemental component of SCAs, with diverse phenomenology, and emphasizes the role of the cerebellum in tremor. Further studies will be useful to delineate the clinical, pathophysiological, and therapeutic aspects of tremor in SCAs.

Reviewing the Structure-Function Paradigm in Polyglutamine Disorders: A Synergistic Perspective on Theoretical and Experimental Approaches

Polyglutamine (polyQ) disorders are a group of neurodegenerative diseases characterized by the excessive expansion of CAG (cytosine, adenine, guanine) repeats within host proteins. The quest to unravel the complex diseases mechanism has led researchers to adopt both theoretical and experimental methods, each offering unique insights into the underlying pathogenesis. This review emphasizes the significance of combining multiple approaches in the study of polyQ disorders, focusing on the structure-function correlations and the relevance of polyQ-related protein dynamics in neurodegeneration. By integrating computational/theoretical predictions with experimental observations, one can establish robust structure-function correlations, aiding in the identification of key molecular targets for therapeutic interventions. PolyQ proteins' dynamics, influenced by their length and interactions with other molecular partners, play a pivotal role in the polyQ-related pathogenic cascade. Moreover, conformational dynamics of polyQ proteins can trigger aggregation, leading to toxic assembles that hinder proper cellular homeostasis. Understanding these intricacies offers new avenues for therapeutic strategies by fine-tuning polyQ kinetics, in order to prevent and control disease progression. Last but not least, this review highlights the importance of integrating multidisciplinary efforts to advancing research in this field, bringing us closer to the ultimate goal of finding effective treatments against polyQ disorders.

Psychometric Validation of the Modified Functional Scale for the Assessment and Rating of Ataxia (f-SARA) in Patients With Spinocerebellar Ataxia

This study aimed to generate evidence to support psychometric validity of the modified functional Scale for the Assessment and Rating of Ataxia (f-SARA) among patients with spinocerebellar ataxia (SCA). Psychometric measurement properties and minimal change thresholds of the f-SARA were evaluated using data from a cohort of SCA subjects (recruited at Massachusetts General Hospital [MGH]; n = 33) and data from a phase 3 trial of troriluzole in adults with SCA (NCT03701399 [Study 206]; n = 217), including a subset of patients with the SCA3 genotype (n = 89). f-SARA item ceiling effects were absent within the MGH cohort, while floor effects were present. Excellent internal consistency reliability was demonstrated (αtotal = 0.90; αitems-removed = 0.86-0.90), and item-to-total correlations were strong (r = 0.82-0.91, per item). High test-retest reliability was demonstrated with intraclass correlation coefficients of 0.91 (total) and 0.73-0.92 (items). Convergent and divergent validity was supported, with strong correlations observed between the f-SARA and similarly constructed scales (FARS-FUNC, BARS, PROM-ADL, and FARS-ADL; all p < 0.001) and weaker correlations observed among measures of differing constructs. Mean item and total scores increased with disease severity (by FARS-FUNC quartile; p < 0.001). A 1-point threshold for meaningful changes was supported as 0.5 × SD = 0.89, SEM = 1.12, and mean changes from baseline for patients classified as "improved," "no change," or "deteriorated" were -0.68, 0.02, and 0.58, respectively. Similar trends were observed in Study 206 all-SCA and SCA3 cohorts. The measurement properties of the f-SARA provide evidence of its psychometric validity, responsiveness, and suitability as a clinical outcome measure in patients with SCA, including those with SCA3.

Emerging Perspectives on Prime Editor Delivery to the Brain

Prime editing shows potential as a precision genome editing technology, as well as the potential to advance the development of next-generation nanomedicine for addressing neurological disorders. However, turning in prime editors (PEs), which are macromolecular complexes composed of CRISPR/Cas9 nickase fused with a reverse transcriptase and a prime editing guide RNA (pegRNA), to the brain remains a considerable challenge due to physiological obstacles, including the blood-brain barrier (BBB). This review article offers an up-to-date overview and perspective on the latest technologies and strategies for the precision delivery of PEs to the brain and passage through blood barriers. Furthermore, it delves into the scientific significance and possible therapeutic applications of prime editing in conditions related to neurological diseases. It is targeted at clinicians and clinical researchers working on advancing precision nanomedicine for neuropathologies.

The Spinocerebellar Ataxia 34-Causing W246G ELOVL4 Mutation Does Not Alter Cerebellar Neuron Populations in a Rat Model

Spinocerebellar ataxia 34 (SCA34) is an autosomal dominant disease that arises from point mutations in the fatty acid elongase, Elongation of Very Long Chain Fatty Acids 4 (ELOVL4), which is essential for the synthesis of Very Long Chain-Saturated Fatty Acids (VLC-SFA) and Very Long Chain-Polyunsaturated Fatty Acids (VLC-PUFA) (28-34 carbons long). SCA34 is considered a neurodegenerative disease. However, a novel rat model of SCA34 (SCA34-KI rat) with knock-in of the W246G ELOVL4 mutation that causes human SCA34 shows early motor impairment and aberrant synaptic transmission and plasticity without overt neurodegeneration. ELOVL4 is expressed in neurogenic regions of the developing brain, is implicated in cell cycle regulation, and ELOVL4 mutations that cause neuroichthyosis lead to developmental brain malformation, suggesting that aberrant neuron generation due to ELOVL4 mutations might contribute to SCA34. To test whether W246G ELOVL4 altered neuronal generation or survival in the cerebellum, we compared the numbers of Purkinje cells, unipolar brush cells, molecular layer interneurons, granule and displaced granule cells in the cerebellum of wildtype, heterozygous, and homozygous SCA34-KI rats at four months of age, when motor impairment is already present. An unbiased, semi-automated method based on Cellpose 2.0 and ImageJ was used to quantify neuronal populations in cerebellar sections immunolabeled for known neuron-specific markers. Neuronal populations and cortical structure were unaffected by the W246G ELOVL4 mutation by four months of age, a time when synaptic and motor dysfunction are already present, suggesting that SCA34 pathology originates from synaptic dysfunction due to VLC-SFA deficiency, rather than aberrant neuronal production or neurodegeneration.

Epidemiology of Spinocerebellar Ataxias in Europe

Spinocerebellar ataxias (SCAs) are a heterogenous group of rare neurodegenerative conditions sharing an autosomal dominant pattern of inheritance. More than 40 SCAs have been genetically determined. However, a systematic review of SCA epidemiology in Europe is still missing. Here we performed a narrative review of the literature on the epidemiology of the most common SCAs in Europe. PubMed, Embase, and MEDLINE were searched from inception until 1 April 2023. All English peer-reviewed articles published were considered and then filtered by abstract examination and subsequently by full text reading. A total of 917 original articles were retrieved. According to the inclusion criteria and after reviewing references for useful papers, a total of 35 articles were included in the review. Overall, SCA3 is the most frequent spinocerebellar ataxia in Europe. Its frequency is strikingly higher in Portugal, followed by Germany, France, and Netherlands. None or few cases were described in Italy, Russia, Poland, Serbia, Finland, and Norway. SCA1 and SCA2 globally displayed similar frequencies, and are more prevalent in Italy, United Kingdom, Poland, Serbia, and France.

Effect of a Home-Base Core Stability Exercises in Hereditary Ataxia. A Randomized Controlled Trial. A Pilot Randomized Controlled Trial

BACKGROUND

Core stability exercises (CSE) have been shown to be effective in improving trunk function in several neurological diseases, but the evidence is scarce on Hereditary Ataxias (HA).

OBJECTIVE

To evaluate the effectiveness of a 5-week home-based CSE program in terms of ataxia severity, trunk function, balance confidence, gait speed, lower limb motor function, quality of life, health status and falls rate in HA individuals at short- and long-term.

METHODS

This is an assessor-blind randomized controlled clinical trial parallel group 1:1. The individuals were divided in experimental group (EG) performed standard care in addition to CSE, and control group (CG) performed standard care alone. The CSE home-program was conducted 1-h/day, 5-day/week for 5-week. The assessment was performed at baseline, endpoint (5-week), and follow-up (10-week). The primary outcomes were ataxia severity assessed by the Scale for the Assessment and Rating of Ataxia and trunk function assessed by Spanish-version of Trunk Impairment Scale 2.0. The secondary outcomes were balance confidence assessed by Activities-specific Balance Confidence (ABC), gait speed by 4-meter walk test (4-MWT), the lower limb motor function by 30-s sit-to-stand, quality of life by EuroQol 5-dimension 5-level (EQ-5D-5L), health-status by EQ-5D and falls rate.

RESULTS

Twenty-three HA individuals were recruited (51.8 ± 11.10 years). Statistically significant group-time interaction was shown in ABC (F:5.539; P = 0.007), EQ-5D-5L Total (F:4.836; P = 0.013), EQ 5D (F:7.207; P = 0.006).

CONCLUSIONS

No statistical differences between groups for ataxia severity and trunk function were observed. However, were differences for balance confidence, gait speed, quality of life, and falls rate in HA individuals.

Health-Related Quality of Life in Patients with Spinocerebellar Ataxia: a Validation Study of the EQ-5D-3L

Although health-related quality of life (HRQoL) has developed into a crucial outcome parameter in clinical research, evidence of the EQ-5D-3L validation performance is lacking in patients with spinocerebellar ataxia (SCA) types 1, 2, 3, and 6. The objective of this study is to assess the acceptability, validity, reliability, and responsiveness of the EQ-5D-3L. For n = 842 predominantly European SCA patients of two longitudinal cohort studies, the EQ-5D-3L, PHQ-9 (Patient Health Questionnaire), and ataxia-specific clinical assessments (SARA: Scale for Assessment and Rating of Ataxia; ADL: activities of daily living as part of Friedreich's Ataxia Rating Scale; INAS: Inventory of Non-Ataxia Signs) were assessed at baseline and multiple annual follow-ups. The EQ-5D-3L was evaluated regarding acceptability, distribution properties, convergent and known-groups validity, test-retest reliability, and effect size measures to analyze health changes. The non-item response was low (EQ-5D-3L index: 0.8%; EQ-VAS: 3.4%). Ceiling effects occurred in 9.9% (EQ-5D-3L) and 3.0% (EQ-VAS) with a mean EQ-5D-3L index of 0.65 ± 0.21. In total, convergent validity showed moderate to strong Spearman's rho (rs > 0.3) coefficients comparing EQ-5D-3L and EQ-VAS with PHQ-9, SARA, ADL, and INAS. EQ-5D-3L could discriminate between groups of age, SARA, ADL, and INAS. Intra-class correlation coefficients (EQ-5D-3LICC: 0.95/EQ-VASICC: 0.88) and Kappa statistics (range 0.44 to 0.93 for EQ-5D-3L items) indicated tolerable reliability. EQ-5D-3L shows small (effect size < 0.3) to moderate (effect size 0.3-0.59) health changes regarding ataxia severity. The analysis confirms an acceptable, reliable, valid, and responsive recommended EQ-5D-3L in SCA patients, measuring the HRQoL adequately, besides well-established clinical instruments.

A GGC-repeat expansion in ZFHX3 encoding polyglycine causes spinocerebellar ataxia type 4 and impairs autophagy

Despite linkage to chromosome 16q in 1996, the mutation causing spinocerebellar ataxia type 4 (SCA4), a late-onset sensory and cerebellar ataxia, remained unknown. Here, using long-read single-strand whole-genome sequencing (LR-GS), we identified a heterozygous GGC-repeat expansion in a large Utah pedigree encoding polyglycine (polyG) in zinc finger homeobox protein 3 (ZFHX3), also known as AT-binding transcription factor 1 (ATBF1). We queried 6,495 genome sequencing datasets and identified the repeat expansion in seven additional pedigrees. Ultrarare DNA variants near the repeat expansion indicate a common distant founder event in Sweden. Intranuclear ZFHX3-p62-ubiquitin aggregates were abundant in SCA4 basis pontis neurons. In fibroblasts and induced pluripotent stem cells, the GGC expansion led to increased ZFHX3 protein levels and abnormal autophagy, which were normalized with small interfering RNA-mediated ZFHX3 knockdown in both cell types. Improving autophagy points to a therapeutic avenue for this novel polyG disease. The coding GGC-repeat expansion in an extremely G+C-rich region was not detectable by short-read whole-exome sequencing, which demonstrates the power of LR-GS for variant discovery.

The Effects of Bacillus amyloliquefaciens SC06 on Behavior and Brain Function in Broilers Infected by Clostridium perfringens

Poultry studies conducted on Clostridium perfringens (CP) mainly focus on the effects of intestinal health and productive performance. Notably, the probiotic Bacillus amyloliquefaciens SC06 (BaSC06) is known to play a role in preventing bacterial infection. However, whether CP could induce the changes in brain function and behaviors and whether BaSC06 could play roles in these parameters is yet to be reported. The aim of this study was to evaluate the effects of BaSC06 on stress-related behaviors and gene expression, as well as the brain morphology and mRNA sequence of the hypothalamus in broiler chickens. A total of 288 one-day-old chicks were randomly divided into four groups: (1) a control group with no treatment administered or infection; (2) birds treated with the BaSC06 group; (3) a CP group; and (4) a BaSC06 plus CP (Ba_CP) group. The results showed that stress and fear-related behaviors were significantly induced by a CP infection and decreased due to the treatment of BaSC06. CP infection caused pathological damage to the pia and cortex of the brain, while BaSC06 showed a protective effect. CP significantly inhibited hypothalamic GABA and promoted HTR1A gene expression, while BaSC06 promoted GABA and decreased HTR1A gene expression. The different genes were nearly found between the comparisons of control vs. Ba group and Ba vs. CP group, while there were a great number of different genes between the comparisons of control vs. Ba_CP as well as CP vs. Ba_CP. Several different gene expression pathways were found that were related to disease, energy metabolism, and nervous system development. Our results will help to promote poultry welfare and health, as well as provide insights into probiotics to replace antibiotics and reduce resistance in the chicken industry.

Development and Validation of SCACOMS, a Composite Scale for Assessing Disease Progression and Treatment Effects in Spinocerebellar Ataxia

Spinocerebellar ataxias (SCA) are rare inherited neurodegenerative disorders characterized by a progressive impairment of gait, balance, limb coordination, and speech. There is currently no composite scale that includes multiple aspects of the SCA experience to assess disease progression and treatment effects. Applying the method of partial least squares (PLS) regression, we developed the Spinocerebellar Ataxia Composite Scale (SCACOMS) from two SCA natural history datasets (NCT01060371, NCT02440763). PLS regression selected items based on their ability to detect clinical decline, with optimized weights based on the item's degree of progression. Following model validation, SCACOMS was leveraged to examine disease progression and treatment effects in a 48-week SCA clinical trial cohort (NCT03701399). Items from the Clinical Global Impression-Global Improvement Scale (CGI-I), the Friedreich Ataxia Rating Scale (FARS) - functional stage, and the Modified Functional Scale for the Assessment and Rating of Ataxia (f-SARA) were objectively selected with weightings based on their sensitivity to clinical decline. The resulting SCACOMS exhibited improved sensitivity to disease progression and greater treatment effects (compared to the original scales from which they were derived) in a 48-week clinical trial of a novel therapeutic agent. The trial analyses also provided a SCACOMS-derived estimate of the temporal delay in SCA disease progression. SCACOMS is a useful composite measure, effectively capturing disease progression and highlighting treatment effects in patients with SCA. SCACOMS will be a powerful tool in future studies given its sensitivity to clinical decline and ability to detect a meaningful clinical impact of disease-modifying treatments.

Preimplantation genetic testing for monogenic disorders (PGT-M) offers an alternative strategy to prevent children from being born with hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes: a retrospective study

BACKGROUND

Preimplantation genetic testing for monogenic disorders (PGT-M) is now widely used as an effective strategy to prevent various monogenic or chromosomal diseases.

MATERIAL AND METHODS

In this retrospective study, couples with a family history of hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes and/or carrying the pathogenic genes underwent PGT-M to prevent children from inheriting disease-causing gene mutations from their parents and developing known genetic diseases. After PGT-M, unaffected (i.e., normal) embryos after genetic detection were transferred into the uterus of their corresponding mothers.

RESULTS

A total of 43 carrier couples with the following hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes underwent PGT-M: Duchenne muscular dystrophy (13 families); methylmalonic acidemia (7 families); spinal muscular atrophy (5 families); infantile neuroaxonal dystrophy and intellectual developmental disorder (3 families each); Cockayne syndrome (2 families); Menkes disease, spinocerebellar ataxia, glycine encephalopathy with epilepsy, Charcot-Marie-Tooth disease, mucopolysaccharidosis, Aicardi-Goutieres syndrome, adrenoleukodystrophy, phenylketonuria, amyotrophic lateral sclerosis, and Dravet syndrome (1 family each). After 53 PGT-M cycles, the final transferable embryo rate was 12.45%, the clinical pregnancy rate was 74.19%, and the live birth rate was 89.47%; a total of 18 unaffected (i.e., healthy) children were born to these families.

CONCLUSIONS

This study highlights the importance of PGT-M in preventing children born with hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes.

Fatigue Impacts Quality of Life in People with Spinocerebellar Ataxias

BACKGROUND

Fatigue is a prevalent and debilitating symptom in neurological disorders, including spinocerebellar ataxias (SCAs). However, the risk factors of fatigue in the SCAs as well as its impact have not been well investigated.

OBJECTIVES

To study the prevalence of fatigue in SCAs, the factors contributing to fatigue, and the influence of fatigue on quality of life.

METHODS

Fatigue was assessed in 418 participants with SCA1, SCA2, SCA3, and SCA6 from the Clinical Research Consortium for the Study of Cerebellar Ataxia using the Fatigue Severity Scale. We conducted multi-variable linear regression models to examine the factors contributing to fatigue as well as the association between fatigue and quality of life.

RESULTS

Fatigue was most prevalent in SCA3 (52.6%), followed by SCA1 (36.7%), SCA6 (35.7%), and SCA2 (35.6%). SCA cases with fatigue had more severe ataxia and worse depressive symptoms. In SCA3, those with fatigue had a longer disease duration and longer pathological CAG repeat numbers. In multi-variable models, depressive symptoms, but not ataxia severity, were associated with more severe fatigue. Fatigue, independent of ataxia and depression, contributed to worse quality of life in SCA3 and SCA6 at baseline, and fatigue continued affecting quality of life throughout the disease course in all types of SCA.

CONCLUSIONS

Fatigue is a common symptom in SCAs and is closely related to depression. Fatigue significantly impacts patients' quality of life. Therefore, screening for fatigue should be considered a part of standard clinical care for SCAs.

Spinocerebellar Ataxia Type 3 Pathophysiology-Implications for Translational Research and Clinical Studies

The spinocerebellar ataxias (SCA) comprise a group of inherited neurodegenerative diseases. Machado-Joseph Disease (MJD) or spinocerebellar ataxia 3 (SCA3) is the most common autosomal dominant form, caused by the expansion of CAG repeats within the ataxin-3 (ATXN3) gene. This mutation results in the expression of an abnormal protein containing long polyglutamine (polyQ) stretches that confers a toxic gain of function and leads to misfolding and aggregation of ATXN3 in neurons. As a result of the neurodegenerative process, SCA3 patients are severely disabled and die prematurely. Several screening approaches, e.g., druggable genome-wide and drug library screenings have been performed, focussing on the reduction in stably overexpressed ATXN3(polyQ) protein and improvement in the resultant toxicity. Transgenic overexpression models of toxic ATXN3, however, missed potential modulators of endogenous ATXN3 regulation. In another approach to identify modifiers of endogenous ATXN3 expression using a CRISPR/Cas9-modified SK-N-SH wild-type cell line with a GFP-T2A-luciferase (LUC) cassette under the control of the endogenous ATXN3 promotor, four statins were identified as potential activators of expression. We here provide an overview of the high throughput screening approaches yet performed to find compounds or genomic modifiers of ATXN3(polyQ) toxicity in different SCA3 model organisms and cell lines to ameliorate and halt SCA3 progression in patients. Furthermore, the putative role of cholesterol in neurodegenerative diseases (NDDs) in general and SCA3 in particular is discussed.

A Review of Ocular Movement Abnormalities in Hereditary Cerebellar Ataxias

Cerebellar ataxias are a wide heterogeneous group of disorders that may present with fine motor deficits as well as gait and balance disturbances that have a significant influence on everyday activities. To review the ocular movements in cerebellar ataxias in order to improve the clinical knowledge of cerebellar ataxias and related subtypes. English papers published from January 1990 to May 2022 were selected by searching PubMed services. The main search keywords were ocular motor, oculomotor, eye movement, eye motility, and ocular motility, along with each ataxia subtype. The eligible papers were analyzed for clinical presentation, involved mutations, the underlying pathology, and ocular movement alterations. Forty-three subtypes of spinocerebellar ataxias and a number of autosomal dominant and autosomal recessive ataxias were discussed in terms of pathology, clinical manifestations, involved mutations, and with a focus on the ocular abnormalities. A flowchart has been made using ocular movement manifestations to differentiate different ataxia subtypes. And underlying pathology of each subtype is reviewed in form of illustrated models to reach a better understanding of each disorder.

Intermuscular Coherence in Spinocerebellar Ataxias 3 and 6: a Preliminary Study

Spinocerebellar ataxias (SCAs) are familial neurodegenerative diseases involving the cerebellum and spinocerebellar tracts. While there is variable involvement of corticospinal tracts (CST), dorsal root ganglia, and motor neurons in SCA3, SCA6 is characterized by a pure, late-onset ataxia. Abnormal intermuscular coherence in the beta-gamma frequency range (IMCβγ) implies a lack of integrity of CST or the afferent input from the acting muscles. We test the hypothesis that IMCβγ has the potential to be a biomarker of disease activity in SCA3 but not SCA6. Intermuscular coherence between biceps brachii and brachioradialis muscles was measured from surface EMG waveforms in SCA3 (N = 16) and SCA6 (N = 20) patients and in neurotypical subjects (N = 23). IMC peak frequencies were present in the β range in SCA patients and in the γ range in neurotypical subjects. The difference between IMC amplitudes in the γ and β ranges was significant when comparing neurotypical control subjects to SCA3 (p < 0.01) and SCA6 (p = 0.01) patients. IMCβγ amplitude was smaller in SCA3 patients compared to neurotypical subjects (p < 0.05), but not different between SCA3 and SCA6 patients or between SCA6 and neurotypical subjects. IMC metrics can differentiate SCA patients from normal controls.

Transcranial Sonography Characteristics of Cerebellar Neurodegenerative Ataxias

Cerebellar neurodegenerative ataxias are a group of disorders affecting the cerebellum and its pathways with different neurological structures. Transcranial sonography (TCS) has been used for the evaluation of brain parenchymal structures in various diseases because of its fast and safe utilization, especially in neuropsychiatric and neurodegenerative diseases. The aim of our study was to investigate TCS characteristics of patients with neurodegenerative cerebellar ataxias. In our study, we included 74 patients with cerebellar degenerative ataxia; 36.5% had autosomal dominant onset, while 33.8% had sporadic onset. Standardized ultrasonographic planes were used for the identification of brain structures of interest. The SARA, INAS, neuropsychological and psychiatric scales were used for the further clinical evaluation of our study participants. The brainstem raphe was discontinued in 33.8% of the patients. The substantia nigra (SN) hyperechogenicity was identified in 79.7%. The third and fourth ventricle enlargement had 79.7% and 45.9% of patients, respectively. A positive and statistically significant correlation was found between SN hyperechogenicity with dystonia (p < 0.01), rigidity and dyskinesia (p < 0.05). The higher SARA total score is statistically significantly correlated with the larger diameter of the III (r = 0.373; p = 0.001) and IV ventricles (r = 0.324; p = 0.005). In such patients, the echogenicity of substantia nigra has been linked to extrapyramidal signs, and raphe discontinuity to depression. Furthermore, ataxia and its clinical subtypes have positively correlated with the IV ventricle diameter, indicating brain atrophy and brain mass reduction.

Phospholipase D, a Novel Therapeutic Target Contributes to the Pathogenesis of Neurodegenerative and Neuroimmune Diseases

Phospholipase D (PLD) is an enzyme that consists of six isoforms (PLD1-PLD6) and has been discovered in different organisms including bacteria, viruses, plants, and mammals. PLD is involved in regulating a wide range of nerve cells' physiological processes, such as cytoskeleton modulation, proliferation/growth, vesicle trafficking, morphogenesis, and development. Simultaneously, PLD, which also plays an essential role in the pathogenesis of neurodegenerative and neuroimmune diseases. In this review, family members, characterizations, structure, functions and related signaling pathways, and therapeutic values of PLD was summarized, then five representative diseases including Alzheimer disease (AD), Parkinson's disease (PD), etc. were selected as examples to tell the involvement of PLD in these neurological diseases. Notably, recent advances in the development of tools for studying PLD therapy envisaged novel therapeutic interventions. Furthermore, the limitations of PLD based therapy were also analyzed and discussed. The content of this review provided a thorough and reasonable basis for further studies to exploit the potential of PLD in the treatment of neurodegenerative and neuroimmune diseases.

Abnormal cortical excitability in patients with spinocerebellar ataxia type 12

BACKGROUND

Spinocerebellar ataxia type 12 (SCA-12) is an uncommon autosomal dominant cerebellar ataxia characterized by action tremors in the upper limbs, dysarthria, head tremor, and gait ataxia. We aimed to evaluate the motor cortical excitability in patients with SCA-12 using transcranial magnetic stimulation (TMS).

METHODS

The study was done in the department of Neurology at the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore. Nine patients with SCA-12 (2 females) and 10 healthy controls (2 females) were included in the study. TMS was performed in all the subjects and various parameters such as resting motor threshold (RMT), central motor conduction time (CMCT) and contralateral silent period (cSP) were recorded. The left motor cortex was stimulated and the recording was done from right first dorsal interossei muscle. The severity of ataxia was assessed using the scale for assessment and rating in ataxia (SARA).

RESULTS

The mean age of the patients was 58.11 ± 7.56 years mean age at onset: 51.67 ± 4.18 years. The mean duration of illness was 9.44 ± 4.88 years. The mean SARA score was 13.83 ± 3.60. Patients with SCA-12 had significantly increased RMT (88.80 ± 12.78 %) compared to HC (44.90 ± 9.40 %, p < 0.05). A significantly prolonged CMCT was observed in patients (13.70 ± 2.52 msec) compared to HC (7.31 ± 1.21 msec, p < 0.05). In addition, cSP was significantly increased in SCA-12 patients (144.43 ± 25.79 msec) compared to HC (82.14 ± 28.90 msec, p < 0.05).

CONCLUSIONS

Patients with SCA-12 demonstrate a reduced cortical excitability and increased cortical inhibition suggesting an increase in the GABAergic neurotransmission.

Cognitive, Emotional, and Other Non-motor Symptoms of Spinocerebellar Ataxias

PURPOSE OF REVIEW

Spinocerebellar ataxias (SCAs) are autosomal dominant degenerative syndromes that present with ataxia and brain stem abnormalities. This review describes the cognitive and behavioral symptoms of SCAs in the context of recent knowledge of the role of the cerebellum in higher intellectual function.

RECENT FINDINGS

Recent studies suggest that patients with spinocerebellar ataxia can display cognitive deficits even early in the disease. These have been given the term cerebellar cognitive affective syndrome (CCAS). CCAS can be tracked using newly developed rating scales. In addition, patients with spinocerebellar ataxia also display impulsive and compulsive behavior, depression, anxiety, fatigue, and sleep disturbances. This review stresses the importance of recognizing non-motor symptoms in SCAs. There is a pressing need for novel therapeutic interventions to address these symptoms given their deleterious impact on patients' quality of life.

Nucleus accumbens degeneration in spinocerebellar ataxia type 2: a preliminary study

BACKGROUND

Spinocerebellar ataxia type 2 (SCA2) exhibits mainly cerebellar and oculomotor dysfunctions but also, frequently, cognitive impairment and neuropsychological symptoms. The mechanism of the progression of SCA2 remains unclear. This study aimed to evaluate longitudinal structural changes in the brains of SCA2 patients based on atrophy rate.

METHODS

The OpenNeuro Dataset ds001378 was used. It comprises the demographic data and two magnetic resonance images each of nine SCA2 patients and 16 healthy controls. All structural images were preprocessed using FreeSurfer software, and each region's bilateral volume was summed. Atrophy rates were calculated based on the concept of symmetrised percent change and compared between SCA2 patients and healthy controls using non-parametric statistics. As post hoc analysis, correlation analysis was performed between infratentorial volume ratio and the accumbens area atrophy rates in SCA2 patients.

RESULTS

There were no significant differences between groups for age, gender, and the time between scans. Statistical analysis indicated a significantly larger atrophy rate of the accumbens area in SCA2 patients than in controls. Additionally, the infratentorial volume ratio and accumbens area atrophy rates showed moderate negative correlation.

CONCLUSIONS

This study found that nucleus accumbens (NAc) atrophy was significantly accelerated in SCA2 patients. Anatomically, the NAc is densely connected with infratentorial brain regions, so it is reasonable to posit that degeneration propagates from the cerebellum and brainstem to the NAc and other supratentorial areas. Functionally, the NAc is essential for appropriate behaviour, so NAc degeneration might contribute to neuropsychological symptoms in SCA2 patients.

Adaptive Long-Read Sequencing Reveals GGC Repeat Expansion in ZFHX3 Associated with Spinocerebellar Ataxia Type 4

BACKGROUND

Spinocerebellar ataxia type 4 (SCA4) is an autosomal dominant ataxia with invariable sensory neuropathy originally described in a family with Swedish ancestry residing in Utah more than 25 years ago. Despite tight linkage to the 16q22 region, the molecular diagnosis has since remained elusive.

OBJECTIVES

Inspired by pathogenic structural variation implicated in other 16q-ataxias with linkage to the same locus, we revisited the index SCA4 cases from the Utah family using novel technologies to investigate structural variation within the candidate region.

METHODS

We adopted a targeted long-read sequencing approach with adaptive sampling on the Oxford Nanopore Technologies (ONT) platform that enables the detection of segregating structural variants within a genomic region without a priori assumptions about any variant features.

RESULTS

Using this approach, we found a heterozygous (GGC)n repeat expansion in the last coding exon of the zinc finger homeobox 3 (ZFHX3) gene that segregates with disease, ranging between 48 and 57 GGC repeats in affected probands. This finding was replicated in a separate family with SCA4. Furthermore, the estimation of this GGC repeat size in short-read whole genome sequencing (WGS) data of 21,836 individuals recruited to the 100,000 Genomes Project in the UK and our in-house dataset of 11,258 exomes did not reveal any pathogenic repeats, indicating that the variant is ultrarare.

CONCLUSIONS

These findings support the utility of adaptive long-read sequencing as a powerful tool to decipher causative structural variation in unsolved cases of inherited neurological disease. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Genetic Myelopathies

OBJECTIVE

This article provides an overview of genetic myelopathies, a diverse group of inherited, degenerative conditions that may be broadly categorized as motor neuron disorders, disorders of spinocerebellar degeneration, leukodystrophies, and hereditary spastic paraplegia. Clinical examples from each category are provided to illustrate the spectrum of genetic myelopathies and their distinguishing features that aid in differentiating genetic myelopathies from potentially treatable acquired causes of myelopathy.

LATEST DEVELOPMENTS

Advances in genetic testing have vastly enhanced current knowledge of genetic myelopathies and the ability to diagnose and provide appropriate counseling to patients and their families. However, potential health care disparities in access to genetic testing is a topic that must be further explored. Although treatment for most of these conditions is typically supportive, there have been recent therapeutic breakthroughs in treatments for amyotrophic lateral sclerosis, spinal muscular atrophy, and Friedreich ataxia.

ESSENTIAL POINTS

Genetic myelopathies may present with chronic and progressive symptoms, a family history of similar symptoms, and involvement of other structures outside of the spinal cord. Imaging often shows spinal cord atrophy, but cord signal change is rare. Exclusion of reversible causes of myelopathy is a key step in the diagnosis. There are many different causes of genetic myelopathies, and in some cases, symptoms may overlap, which underscores the utility of genetic testing in confirming the precise underlying neurologic condition.

Intracranial Gene Delivery Mediated by Albumin-Based Nanobubbles and Low-Frequency Ultrasound

Research in the field of high-intensity focused ultrasound (HIFU) for intracranial gene therapy has greatly progressed over the years. However, limitations of conventional HIFU still remain. That is, genes are required to cross the blood-brain barrier (BBB) in order to reach the neurological disordered lesion. In this study, we introduce a novel direct intracranial gene delivery method, bypassing the BBB using human serum albumin-based nanobubbles (NBs) injected through a less invasive intrathecal route via lumbar puncture, followed by intracranial irradiation with low-frequency ultrasound (LoFreqUS). Focusing on both plasmid DNA (pDNA) and messenger RNA (mRNA), our approach utilizes LoFreqUS for deeper tissue acoustic penetration and enhancing gene transfer efficiency. This drug delivery method could be dubbed as the "Spinal Back-Door Approach", an alternative to the "front door" BBB opening method. Experiments showed that NBs effectively responded to LoFreqUS, significantly improving gene transfer in vitro using U-87 MG cell lines. In vivo experiments in mice demonstrated significantly increased gene expression with pDNA; however, we were unable to obtain conclusive results using mRNA. This novel technique, combining albumin-based NBs and LoFreqUS offers a promising, efficient, targeted, and non-invasive solution for central nervous system gene therapy, potentially transforming the treatment landscape for neurological disorders.

The natural breakthrough: phytochemicals as potent therapeutic agents against spinocerebellar ataxia type 3

There is no FDA-approved drug for neurological disorders like spinocerebellar ataxia type 3. CAG repeats mutation in the ATXN3 gene, causing spinocerebellar ataxia type 3 disease. Symptoms include sleep cycle disturbance, neurophysiological abnormalities, autonomic dysfunctions, and depression. This research focuses on drug discovery against ATXN3 using phytochemicals of different plants. Three phytochemical compounds (flavonoids, diterpenoids, and alkaloids) were used as potential drug candidates and screened against the ATXN3 protein. The 3D structure of ATXN3 protein and phytochemicals were retrieved and validation of the protein was 98.1% Rama favored. The protein binding sites were identified for the interaction by CASTp. ADMET was utilized for the pre-clinical analysis, including solubility, permeability, drug likeliness and toxicity, and chamanetin passed all the ADMET properties to become a lead drug candidate. Boiled egg analysis attested that the ligand could cross the gastrointestinal tract. Pharmacophore analysis showed that chamanetin has many hydrogen acceptors and donors which can form interaction bonds with the receptor proteins. Chamanetin passed all the screening analyses, having good absorption, no violation of Lipinski's rule, nontoxic properties, and good pharmacophore properties. Chamanetin was one of the lead compounds with a - 7.2 kcal/mol binding affinity after screening the phytochemicals. The stimulation of ATXN3 showed stability after 20 ns of interaction in an overall 50 ns MD simulation. Chamanetin (Flavonoid) was predicted to be highly active against ATXN3 with good drug-like properties. In-silico active drug against ATXN3 from a plant source and good pharmacokinetics parameters would be excellent drug therapy for SC3, such as flavonoids (Chamanetin).

Methods for evaluating gait associated dynamic balance and coordination in rodents

Balance is the dynamic and unconscious control of the body's centre of mass to maintain postural equilibrium. Regulated by the vestibular system, head movement and acceleration are processed by the brain to adjust joints. Several conditions result in a loss of balance, including Alzheimer's Disease, Parkinson's Disease, Menière's Disease and cervical spondylosis, all of which are caused by damage to certain parts of the vestibular pathways. Studies about the impairment of the vestibular system are challenging to carry out in human trials due to smaller study sizes limiting applications of the results and a lacking understanding of the human balance control mechanism. In contrast, more controlled research can be performed in animal studies which have fewer confounding factors than human models and allow specific conditions that affect balance to be replicated. Balance control can be studied using rodent balance-related behavioural tests after spinal or brain lesions, such as the Basso, Beattie and Bresnahan (BBB) Locomotor Scale, Foot Fault Scoring System, Ledged Beam Test, Beam Walking Test, and Ladder Beam Test, which are discussed in this review article along with their advantages and disadvantages. These tests can be performed in preclinical rodent models of femoral nerve injury, stroke, spinal cord injury and neurodegenerative diseases.

Cranial Nerve Thinning Distinguishes RFC1-Related Disorder from Other Late-Onset Ataxias

BACKGROUND

RFC1-related disorder (RFC1/CANVAS) shares clinical features with other late-onset ataxias, such as spinocerebellar ataxias (SCA) and multiple system atrophy cerebellar type (MSA-C). Thinning of cranial nerves V (CNV) and VIII (CNVIII) has been reported in magnetic resonance imaging (MRI) scans of RFC1/CANVAS, but its specificity remains unclear.

OBJECTIVES

To assess the usefulness of CNV and CNVIII thinning to differentiate RFC1/CANVAS from SCA and MSA-C.

METHODS

Seventeen individuals with RFC1/CANVAS, 57 with SCA (types 2, 3 and 6), 11 with MSA-C and 15 healthy controls were enrolled. The Balanced Fast Field Echo sequence was used for assessment of cranial nerves. Images were reviewed by a neuroradiologist, who classified these nerves as atrophic or normal, and subsequently the CNV was segmented manually by an experienced neurologist. Both assessments were blinded to patient and clinical data. Non-parametric tests were used to assess between-group comparisons.

RESULTS

Atrophy of CNV and CNVIII, both alone and in combination, was significantly more frequent in the RFC1/CANVAS group than in healthy controls and all other ataxia groups. Atrophy of CNV had the highest sensitivity (82%) and combined CNV and CNVIII atrophy had the best specificity (92%) for diagnosing RFC1/CANVAS. In the quantitative analyses, CNV was significantly thinner in the RFC1/CANVAS group relative to all other groups. The cutoff CNV diameter that best identified RFC1/CANVAS was ≤2.2 mm (AUC = 0.91; sensitivity 88.2%, specificity 95.6%).

CONCLUSION

MRI evaluation of CNV and CNVIII using a dedicated sequence is an easy-to-use tool that helps to distinguish RFC1/CANVAS from SCA and MSA-C.

Genetic Interventions for Spinocerebellar Ataxia and Huntington's Disease: A Qualitative Study of the Patient Perspective

Background

For various genetic disorders characterized by expanded cytosine-adenine-guanine (CAG) repeats, such as spinocerebellar ataxia (SCA) subtypes and Huntington's disease (HD), genetic interventions are currently being tested in different clinical trial phases. The patient's perspective on such interventions should be included in the further development and implementation of these new treatments.

Objective

To obtain insight into the thoughts and perspectives of individuals with SCA and HD on genetic interventions.

Methods

In this qualitative study, participants were interviewed using semi-structured interview techniques. Topics discussed were possible risks and benefits, and logistic factors such as timing, location and expertise. Data were analyzed using a generic thematic analysis. Responses were coded into superordinate themes.

Results

Ten participants (five with SCA and five with HD) were interviewed. In general, participants seemed to be willing to undergo genetic interventions. Important motives were the lack of alternative disease-modifying treatment options, the hope for slowing down disease progression, and preservation of current quality of life. Before undergoing genetic interventions, participants wished to be further informed. Logistic factors such as mode and frequency of administration, expertise of the healthcare provider, and timing of treatment are of influence in the decision-making process.

Conclusions

This study identified assumptions, motives, and topics that require further attention before these new therapies, if proven effective, can be implemented in clinical practice. The results may help in the design of care pathways for genetic interventions for these and other rare genetic movement disorders.

Exploring the Therapeutic Potential of Phytoconstituents for Addressing Neurodegenerative Disorders

Neurodegenerative disorder is a serious condition that is caused by abnormal or no neurological function. Neurodegenerative disease is a major growing cause of mortality and morbidity worldwide, especially in the elderly. After World War Ⅱ, eugenics term was exterminated from medicines. Neurodegenerative disease is a genetically inherited disease. Lifestyle changes, environmental factors, and genetic modification, together or alone, are involved in the occurrence of this disorder. The major examples of neurodegenerative disorders are Alzheimer's and Parkinson's disease, in which apoptosis and necrosis are the two major death pathways for neurons. It has been determined from various studies that the etiology of the neurodegenerative disease involves the role of oxidative stress and anti-oxidant defence system, which are prime factors associated with the activation of signal transduction pathway that is responsible for the formation of synuclein in the brain and manifestation of toxic reactions in the form of functional abnormality, which ultimately leads to the dysfunction of neuronal pathway or cell. There has not been much success in the discovery of effective therapy to treat neurodegenerative diseases because the main cause of abnormal functioning or death of neurons is not well known. However, the use of natural products that are derived from plants has effective therapeutic potential against neurodegenerative disease. The natural compounds with medicinal properties to prevent neurological dysfunction are curcumin, wolfberry, ginseng, and Withania somnifera. The selection and use of natural compounds are based on their strong anti-inflammatory and anti-oxidant properties against neurodegenerative disease. Herbal products have active constituents that play an important role in the prevention of communication errors between neurons and neurotransmitters and their respective receptors in the brain, which influence their function. Considering this, natural products have great potential against neurodegenerative diseases. This article reviews the natural compounds used to treat neurodegenerative diseases and their mechanisms of action.

The molecular mechanisms of spinocerebellar ataxias for DNA repeat expansion in disease

Spinocerebellar ataxias (SCAs) are a heterogenous group of neurodegenerative disorders which commonly inherited in an autosomal dominant manner. They cause muscle incoordination due to degeneration of the cerebellum and other parts of nervous system. Out of all the characterized (>50) SCAs, 14 SCAs are caused due to microsatellite repeat expansion mutations. Repeat expansions can result in toxic protein gain-of-function, protein loss-of-function, and/or RNA gain-of-function effects. The location and the nature of mutation modulate the underlying disease pathophysiology resulting in varying disease manifestations. Potential toxic effects of these mutations likely affect key major cellular processes such as transcriptional regulation, mitochondrial functioning, ion channel dysfunction and synaptic transmission. Involvement of several common pathways suggests interlinked function of genes implicated in the disease pathogenesis. A better understanding of the shared and distinct molecular pathogenic mechanisms in these diseases is required to develop targeted therapeutic tools and interventions for disease management. The prime focus of this review is to elaborate on how expanded 'CAG' repeats contribute to the common modes of neurotoxicity and their possible therapeutic targets in management of such devastating disorders.

Incidence of different pressure patterns of spinal cerebellar ataxia and analysis of imaging and genetic diagnosis

Neurologists have a difficult time identifying sporadic cerebellar ataxia. Multiple system atrophy of the cerebellar type (MSA-C), spontaneous late cortical cerebellar atrophy, and prolonged alcohol use are a few possible causes. In a group of people with sporadic cerebellar ataxia that was not MSA-C, an autosomal-dominant spinocerebellar ataxia (SCA) mutation was recently discovered. Chinese single-hospital cohort will be used in this study to genetic screen for SCA-related genes. One hundred forty individuals with CA were monitored over 8 years. Thirty-one individuals had familial CA, 109 patients had sporadic CA, 73 had MSA-C, and 36 had non-MSA-C sporadic CA. In 28 of the 31 non-MSA-C sporadic patients who requested the test, we carried out gene analysis, including SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA12, SCA17, SCA31, and dentatorubro-pallidoluysian atrophy (DRPLA). The control group consisted of family members of the patients. In 57% of the instances with spontaneous CA that were not MSA-C, gene abnormalities were discovered. The most frequent exception among individuals with sporadic CA was SCA6 (36%), followed by monsters in SCA1, 2, 3, 8, and DRPLA. In contrast, 75% of the patients with familial CA had gene abnormalities, the most frequent of which was SCA6 abnormality. The age of 69 vs 59 was higher, and the CAG repeat length was a minor age of 23 vs 25 in the former instances compared to the last one among individuals with SCA6 anomalies that were sporadic as opposed to familial cases. In sporadic CA, autosomal-dominant mutations in SCA genes, notably in SCA6, are common. Although the cause of the increased incidence of SCA6 mutations is unknown, it may be related to a greater age of onset and varied penetrance of SCA6 mutations.

Structural and mechanistic insights into disease-associated endolysosomal exonucleases PLD3 and PLD4

Endolysosomal exonucleases PLD3 and PLD4 (phospholipases D3 and D4) are associated with autoinflammatory and autoimmune diseases. We report structures of these enzymes, and the molecular basis of their catalysis. The structures reveal an intra-chain dimer topology forming a basic active site at the interface. Like other PLD superfamily members, PLD3 and PLD4 carry HxKxxxxD/E motifs and participate in phosphodiester-bond cleavage. The enzymes digest ssDNA and ssRNA in a 5'-to-3' manner and are blocked by 5'-phosphorylation. We captured structures in apo, intermediate, and product states and revealed a 'link-and-release' two-step catalysis. We also unexpectedly demonstrated phosphatase activity via a covalent 3' phosphistidine intermediate. PLD4 contains an extra hydrophobic clamp that stabilizes substrate and could affect oligonucleotide substrate preference and product release. Biochemical and structural analysis of disease-associated mutants of PLD3/4 demonstrated reduced enzyme activity or thermostability and the possible basis for disease association. Furthermore, these findings provide insight into therapeutic design.

Disability in cerebellar ataxia syndromes is linked to cortical degeneration

OBJECTIVE

We aimed to relate clinical measures of disability in chronic cerebellar degeneration to structural whole-brain changes using voxel-based and surface-based morphometry (vbm and sbm). We were particularly interested in remote effects of cerebellar degeneration in the cerebral cortex.

METHODS

We recruited 30 patients with cerebellar degeneration of different aetiologies (downbeat nystagmus syndrome, DBN n = 14, spinocerebellar ataxia, SCA n = 9, sporadic adult late-onset ataxia, SAOA n = 7). All patients were thoroughly characterised in the motor, cognitive, vestibular and ocular-motor domains. Vbm and sbm were used to evaluate structural differences between cerebellar degeneration patients and a group of healthy age- and gender-matched volunteers. Linear regression models were used to correlate functional measures of disease progression and postural stability with whole brain volumetry.

RESULTS

Patients with SCA and SAOA showed widespread volume loss in the cerebellar hemispheres and less prominently in the vermis. Patients with DBN showed a distinct pattern of grey matter volume (GMV) loss that was restricted to the vestibular and ocular-motor representations in lobules IX, X and V-VII. Falls were associated with brainstem white matter volume. VBM and SBM linear regression models revealed associations between severity of ataxic symptoms, cognitive performance and preferred gait velocity. This included extra-cerebellar (sub-)cortical hubs of the motor and locomotion network (putamen, caudate, thalamus, primary motor cortex, prefrontal cortex) and multisensory areas involved in spatial navigation and cognition.

CONCLUSION

Functional disability in multiple domains was associated with structural changes in the cerebral cortex.

Injury of the Vestibulocerebellar Tract and Signs of Ataxia in Patients with Cerebellar Stroke

BACKGROUND

The vestibulocerebellar tract (VCT) is responsible for maintaining balance, spatial orientation, and coordination. Damage to the vestibular system is accompanied by symptoms of balance disorder or ataxia. This study aimed to compare cerebellar dysfunction according to VCT damage in patients with cerebellar stroke.

METHODS

Six patients with cerebellum injury were recruited. This study measured ataxia and hand function related to visuomotor integration and manual dexterity using the Purdue pegboard test. The primary and bilateral secondary VCTs were reconstructed to investigate the integrity of pathways using diffusion tensor imaging (DTI).

RESULTS

The ataxia sign was positive in five patients (83%) at onset. In the result of the pegboard test, all patients had hand dysfunction in the dominant hand (100%). Likewise, all patients also had non-dominant hand dysfunction (100%). On the DTI tractography, the left and right primary VCTs of the patients demonstrated a 25% injury rate. Furthermore, the injury rates of ipsilateral and contralateral secondary VCTs were 50% and 58%.

CONCLUSIONS

Ataxia is related to secondary VCTs, and hand dysfunction is also related to VCTs. Therefore, we believe that the current study will be helpful in evaluating and providing a clinical intervention strategy for patients with ataxia and hand dysfunction following cerebellar injury.

A Novel c.3636-4 A&gt;G Mutation in the CCDC88C Plays a Causative Role in Familial Spinocerebellar Ataxia

INTRODUCTION

Spinocerebellar ataxia (SCA) is an autosomal dominant genetic disease characterized by cerebellar neurological deficits. Specifically, its primary clinical manifestation is ataxia accompanied by peripheral nerve damage. A total of 48 causative genes of SCA have been identified. This study aimed to identify causative genes of autosomal dominant SCA in a four-generation Chinese kindred comprising eight affected individuals.

METHODS

Genomic DNA samples were extracted from the pedigree members, and genomic whole-exome sequencing was performed, followed by bidirectional Sanger sequencing, and minigene assays to identify mutation sites.

RESULTS

A novel pathogenic heterozygous mutation in the splice region of the coiled-coil domain containing the 88C (CCDC88C) gene (NM_001080414:c.3636-4 A>G) was identified in four affected members. The minigene assay results indicated that this mutation leads to the insertion of CAG bases (c.3636-1_3636-3 insCAG).

CONCLUSION

CCDC88C gene mutation leads to SCA40 (OMIM:616053), which is a rare subtype of SCA without symptoms during childhood. Our findings further demonstrated the role of the CCDC88C gene in SCA and indicated that the c.3636-4 A>G (NM_001080414) variant of CCDC88C is causative for a later-onset phenotype of SCA40. Our findings enrich the mutation spectrum of CCDC88C gene and provide a theoretical basis for the genetic counseling of SCA40.