Elderberry diet enhances motor performance and reduces neuroinflammation-induced cell death in cerebellar ataxia rat models

Cerebellar ataxia (CA) is a condition in which cerebellar dysfunction results in movement disorders such as dysmetria, synergy and dysdiadochokinesia. This study investigates the therapeutic effects of elderberry (EB) diet on the 3-acetylpyridine-induced (3-AP) CA rat model. First, CA rat models were generated by 3-AP administration followed by elderberry diet treatment containing 2 % EB for 8 consecutive weeks. Motor performance, electromyographic activity and gene expression were then evaluated. The number of Purkinje neurons were evaluated by stereological methods. Immunohistochemistry for the microgliosis, astrogliosis and apoptosis marker caspase-3 was also performed. In addition, the morphology of microglia and astrocytes was assessed using the Sholl analysis method. The results showed that EB diet administration in a 3-AP ataxia model improved motor coordination, locomotor activity and neuro-muscular function, prevented Purkinje neurons degeneration, increased microglia and astrocyte complexity and reduced cell soma size. Moreover, EB diet administration decreased apoptosis in cerebellum of 3-AP ataxic model. In addition, elderberry diet treatment decreased the expression of inflammatory, apoptotic and necroptotic genes and increased the expression of antioxidant-related genes. The results suggest that the EB diet attenuates 3-AP-induced neuroinflammation leading to cell death and improves motor performance. Thus, the EB diet could be used as a therapeutic procedure for CA due to its neuroprotective effects.

Hereditary Ataxias: From Bench to Clinic, Where Do We Stand?

Cerebellar ataxias are a wide heterogeneous group of movement disorders. Within this broad umbrella of diseases, there are both genetics and sporadic forms. The clinical presentation of these conditions can exhibit a diverse range of symptoms across different age groups, spanning from pure cerebellar manifestations to sensory ataxia and multisystemic diseases. Over the last few decades, advancements in our understanding of genetics and molecular pathophysiology related to both dominant and recessive ataxias have propelled the field forward, paving the way for innovative therapeutic strategies aimed at preventing and arresting the progression of these diseases. Nevertheless, the rarity of certain forms of ataxia continues to pose challenges, leading to limited insights into the etiology of the disease and the identification of target pathways. Additionally, the lack of suitable models hampers efforts to comprehensively understand the molecular foundations of disease's pathophysiology and test novel therapeutic interventions. In the following review, we describe the epidemiology, symptomatology, and pathological progression of hereditary ataxia, including both the prevalent and less common forms of these diseases. Furthermore, we illustrate the diverse molecular pathways and therapeutic approaches currently undergoing investigation in both pre-clinical studies and clinical trials. Finally, we address the existing and anticipated challenges within this field, encompassing both basic research and clinical endeavors.

A Pilot Study to Develop Paraneoplastic Cerebellar Degeneration Mouse Model

Modeling paraneoplastic neurological diseases to understand the immune mechanisms leading to neuronal death is a major challenge given the rarity and terminal access of patients' autopsies. Here, we present a pilot study aiming at modeling paraneoplastic cerebellar degeneration with Yo autoantibodies (Yo-PCD). Female mice were implanted with an ovarian carcinoma cell line expressing CDR2 and CDR2L, the known antigens recognized by anti-Yo antibodies. To boost the immune response, we also immunized the mice by injecting antigens with diverse adjuvants and immune checkpoint inhibitors. Ataxia and gait instability were assessed in treated mice as well as autoantibody levels, Purkinje cell density, and immune infiltration in the cerebellum. We observed the production of anti-Yo antibodies in the CSF and serum of all immunized mice. Brain immunoreaction varied depending on the site of implantation of the tumor, with subcutaneous administration leading to a massive infiltration of immune cells in the meningeal spaces, choroid plexus, and cerebellar parenchyma. However, we did not observe massive Purkinje cell death nor any motor impairments in any of the experimental groups. Self-sustained neuro-inflammation might require a longer time to build up in our model. Unusual tumor antigen presentation and/or intrinsic, species-specific factors required for pro-inflammatory engagement in the brain may also constitute strong limitations to achieve massive recruitment of antigen-specific T-cells and killing of antigen-expressing neurons in this mouse model.

Autoantibodies against eukaryotic translation elongation factor 1 delta in two patients with autoimmune cerebellar ataxia

Background

Autoantibodies are useful biomarkers for the early detection and diagnosis of autoimmune cerebellar ataxia (ACA).

Objective

To identify novel autoantibody candidates in ACA patients.

Methods

Patients with cerebellar ataxia of unknown cause were recruited from July 2018 to February 2023. Anti-neural autoantibodies in patient samples were detected by tissue-based indirect immunofluorescence assay (TBA) on rat cerebellum sections. TBA-positive samples were further screened for well-established anti-neural autoantibodies using commercial kits. Tissue-immunoprecipitation (TIP) and subsequent mass spectrometric (MS) analysis were used to explore the target antigens of autoantibodies in samples that were TBA-positive but negative for known autoantibodies. The specific binding between autoantibodies and the identified target antigen was confirmed by neutralization experiments, recombinant cell-based indirect immunofluorescence assay (CBA), and western blotting experiments.

Results

The eukaryotic translation elongation factor 1 delta (EEF1D) protein was identified as a target antigen of autoantibodies in samples from a 43-year-old female ACA patient, while the specific binding of autoantibodies and EEF1D was confirmed by subsequent experiments. A second anti-EEF1D autoantibody-positive ACA patient, a 59-year-old female, was detected in simultaneous screening. The main clinical manifestations in each of the two patients were cerebellar syndrome, such as unsteady walking and limb ataxia. Both patients received immunotherapy, including corticosteroids, intravenous immunoglobulin, and mycophenolate mofetil. Their outcomes provided evidence to support the effectiveness of immunotherapy, but the cerebellar atrophy that occurred before treatment may be irreversible.

Conclusion

In the current study, we identified anti-EEF1D autoantibody as a novel autoantibody candidate in ACA. Its pathological roles and diagnostic value need to be further verified in larger-scale studies.

An atypical case of hypomagnesemia-induced cerebellar syndrome with literature review

Cerebellar ataxia in adults is always a diagnostic challenge. One of the important causes of late-onset cerebellar ataxia is hypomagnesemia. Hypomagnesemia can have varied manifestations and is attributable to numerous causes. Identification of hypomagnesemia-induced cerebellar syndrome (HiCS) is important as it is reversible but often missed. HiCS has distinct clinical findings and characteristic magnetic resonance imaging (MRI) findings. HiCS presents with distinct clinical, biochemical, and neuroimaging findings, but it cannot be ruled out even in the absence of neuroimaging findings. This condition has to be treated promptly and meticulously to avoid precipitating any serious complications, and a strong suspicion is required for the diagnosis. The underlying cause should be evaluated and managed, as HiCS is a serious but potentially reversible disease with a good prognosis. We present a case of HiCS presenting with a characteristic history of recurrent ataxia, tremor, and vertigo that improved with treatment. Our patient was atypical, as there were no significant MRI findings attributable to hypomagnesemia. Only seven case reports are available throughout the world that show such disparity.

A Systematic Review on Anti-Yo/PCA-1 Antibody: Beyond Cerebellar Ataxia in Middle-Aged Women with Gynecologic Cancer

Current understanding of anti-Yo/PCA1 antibody-associated cerebellar ataxia is based on case reports and small case series. Our goal was to summarize clinical features, highlighting atypical presentations and gaps of knowledge. Following the PRISMA guidelines, we systematically screened Pubmed/MEDLINE, Embase, Scopus, and Web of Science from inception to April 2022 for all case reports and series concerning anti-Yo antibody-associated cerebellar ataxia. We collected data on clinical presentation, investigation findings, and treatment outcomes. Of 379 included patients, 96% were female with gynecologic cancer (82%). Among men, 87% had an associated tumor, mainly of gastrointestinal origin. The median age was 60 years old. Pancerebellar ataxia was the main clinical feature, but extracerebellar findings were frequent during the disease course. Vertigo and imbalance can be present early in the disease course in about two thirds of patients, as a prodromal phase. Although neuroimaging usually is normal or shows cerebellar atrophy, inflammatory changes may also be present. More than half of the patients reported some improvement after immunotherapy. However, despite treatment, 84% of survivors were unable to walk unassisted on follow-up. Our study provides objective data and advances in current knowledge of anti-Yo antibody-associated cerebellar ataxia such as the description of prodromal symptoms, extracerebellar findings, and its presentations in males.

Immune-mediated ataxias: Guide to clinicians

Immune-mediated cerebellar ataxias were initially described as a clinical entity in the 1980s, and since then, an expanding body of evidence has contributed to our understanding of this topic. These ataxias encompass various etiologies, including postinfectious cerebellar ataxia, gluten ataxia, paraneoplastic cerebellar degeneration, opsoclonus-myoclonus-ataxia syndrome and primary autoimmune cerebellar ataxia. The increased permeability of the brain-blood barrier could potentially explain the vulnerability of the cerebellum to autoimmune processes. In this manuscript, our objective is to provide a comprehensive review of the most prevalent diseases within this group, emphasizing clinical indicators, pathogenesis, and current treatment approaches.

Two unrelated fetuses with ITPR1 missense variants and fetal hydrops

We describe two fetuses from unrelated families with likely pathogenic variants in ITPR1 that presented with nonimmune fetal hydrops. Trio exome sequencing revealed a de novo heterozygous likely pathogenic missense variant c.7636G > A (p.Val2531Met) in ITPR1 (NM_001378452.1) in proband 1 and a de novo heterozygous likely pathogenic missense variant c.34G > A [p.Gly12Arg] in proband 2. Variants in ITPR1 have been associated with several genetic conditions, including spinocerebellar ataxia 15, spinocerebellar ataxia 29, and Gillespie syndrome. Our report on two patients details a previously undescribed severe fetal presentation of nonimmune hydrops fetalis associated with missense variants in the ITPR1 gene.

Advances in cerebellar disorders: pre-clinical models, therapeutic targets, and challenges

INTRODUCTION

Cerebellar ataxias (CAs) represent neurological disorders with multiple etiologies and a high phenotypic variability. Despite progress in the understanding of pathogenesis, few therapies are available so far. Closing the loop between preclinical studies and therapeutic trials is important, given the impact of CAs upon patients' health and the roles of the cerebellum in multiple domains. Because of a rapid advance in research on CAs, it is necessary to summarize the main findings and discuss future directions.

AREAS COVERED

We focus our discussion on preclinical models, cerebellar reserve, the therapeutic management of CAs, and suitable surrogate markers. We searched Web of Science and PubMed using keywords relevant to cerebellar diseases, therapy, and preclinical models.

EXPERT OPINION

There are many symptomatic and/or disease-modifying therapeutic approaches under investigation. For therapy development, preclinical studies, standardization of disease evaluation, safety assessment, and demonstration of clinical improvements are essential. Stage of the disease and the level of the cerebellar reserve determine the goals of the therapy. Deficits in multiple categories and heterogeneity of CAs may require disease-, stage-, and symptom-specific therapies. More research is needed to clarify how therapies targeting the cerebellum influence both basal ganglia and the cerebral cortex, poorly explored domains in CAs.

The Acute Superficial Siderosis Syndrome - Clinical Entity, Imaging Findings, and Histopathology

Superficial siderosis is a consequence of repetitive bleeding into the subarachnoid space, leading to toxic iron and hemosiderin deposits on the surface of the brain and spine. The clinical and radiological phenotypes of superficial siderosis are known to manifest over long time intervals. In contrast, this study defines the "acute superficial siderosis syndrome" and illustrates typical imaging and histopathological findings of this entity. We describe the case of a 61-year-old male patient who was diagnosed with a melanoma metastasis in the right frontal cortex in February 2019. Within a few weeks he developed a progressive syndrome characterized by cerebellar ataxia, gait disturbance, signs of myelopathy, and radiculopathy. MRI revealed ongoing hemorrhage from the metastasis into the lateral ventricle and the subarachnoid space. A semiquantitative assessment of three subsequent MRI within an 8-week period documented the rapid development of superficial siderosis along the surface of the cerebellum, the brain stem, and the lower parts of the supratentorial regions on T2*-weighted sequences. The diagnosis of a superficial siderosis was histopathologically confirmed by identifying iron and hemosiderin deposits on the cortex along with astrogliosis. The recognition of this "acute superficial siderosis syndrome" triggered surgical removal of the hemorrhagic metastasis. Based on a single case presentation, we define the "acute superficial siderosis syndrome" as a clinical entity and describe the radiological and histopathological characteristics of this entity. Early recognition of this syndrome may allow timely elimination of the bleeding source, in order to prevent further clinical deterioration.

Psychiatric-Like Impairments in Mouse Models of Spinocerebellar Ataxias

Many patients with spinocerebellar ataxia (SCA) suffer from diverse neuropsychiatric issues, including memory impairments, apathy, depression, or anxiety. These neuropsychiatric aspects contribute per se to the reduced quality of life and worse prognosis. However, the extent to which SCA-related neuropathology directly contributes to these issues remains largely unclear. Behavioral profiling of various SCA mouse models can bring new insight into this question. This paper aims to synthesize recent findings from behavioral studies of SCA patients and mouse models. The role of SCA neuropathology for shaping psychiatric-like impairments may be exemplified in mouse models of SCA1. These mice evince robust cognitive impairments which are shaped by both the cerebellar as well as out-of-cerebellar pathology. Although emotional-related alternations are also present, they seem to be less robust and more affected by the specific distribution and character of the neuropathology. For example, cerebellar-specific pathology seems to provoke behavioral disinhibition, leading to seemingly decreased anxiety, whereas complex SCA1 neuropathology induces anxiety-like phenotype. In SCA1 mice with complex neuropathology, some of the psychiatric-like impairments are present even before marked cerebellar degeneration and ataxia and correlate with hippocampal atrophy. Similarly, complete or partial deletion of the implicated gene (Atxn1) leads to cognitive dysfunction and anxiety-like behavior, respectively, without apparent ataxia and cerebellar degeneration. Altogether, these findings collectively suggest that the neuropsychiatric issues have a biological basis partially independent of the cerebellum. As some neuropsychiatric issues may stem from weakening the function of the implicated gene, therapeutic reduction of its expression by molecular approaches may not necessarily mitigate the neuropsychiatric issues.

Deep Intronic FGF14 GAA Repeat Expansion in Late-Onset Cerebellar Ataxia

BACKGROUND

The late-onset cerebellar ataxias (LOCAs) have largely resisted molecular diagnosis.

METHODS

We sequenced the genomes of six persons with autosomal dominant LOCA who were members of three French Canadian families and identified a candidate pathogenic repeat expansion. We then tested for association between the repeat expansion and disease in two independent case-control series - one French Canadian (66 patients and 209 controls) and the other German (228 patients and 199 controls). We also genotyped the repeat in 20 Australian and 31 Indian index patients. We assayed gene and protein expression in two postmortem cerebellum specimens and two induced pluripotent stem-cell (iPSC)-derived motor-neuron cell lines.

RESULTS

In the six French Canadian patients, we identified a GAA repeat expansion deep in the first intron of FGF14, which encodes fibroblast growth factor 14. Cosegregation of the repeat expansion with disease in the families supported a pathogenic threshold of at least 250 GAA repeats ([GAA]_≥250). There was significant association between FGF14 (GAA)_≥250 expansions and LOCA in the French Canadian series (odds ratio, 105.60; 95% confidence interval [CI], 31.09 to 334.20; P<0.001) and in the German series (odds ratio, 8.76; 95% CI, 3.45 to 20.84; P<0.001). The repeat expansion was present in 61%, 18%, 15%, and 10% of French Canadian, German, Australian, and Indian index patients, respectively. In total, we identified 128 patients with LOCA who carried an FGF14 (GAA)_≥250 expansion. Postmortem cerebellum specimens and iPSC-derived motor neurons from patients showed reduced expression of FGF14 RNA and protein.

CONCLUSIONS

A dominantly inherited deep intronic GAA repeat expansion in FGF14 was found to be associated with LOCA. (Funded by Fondation Groupe Monaco and others.).

The Role of Imaging Studies in Favor of Possible Cerebellar Multiple System Atrophy: A Case Study

ABSTRACT

We report a 64-year-old woman whose history started with urinary incontinence and neurological symptoms (cognitive impairment, dysarthria, and gait difficulties). The 18F-FDG PET/CT showed hypometabolism of the whole cerebellum. Then 6 months later, she developed tremor, postural instability, and ataxia, so she was hospitalized to complete study. Blood tests (antibodies, vitamin B12, copper, genetic test of spinocerebellar ataxia) did not have alterations, but imaging studies, along with clinical symptoms, provide the diagnosis of possible multiple system atrophy.

The Intersection Between Cerebellar Ataxia and Neuropathy: a Proposed Classification and a Diagnostic Approach

Neuropathy is a common associated feature of different types of genetic or sporadic cerebellar ataxias. The pattern of peripheral nerve involvement and its associated clinical features can be an invaluable aspect for narrowing the etiologic diagnosis in the investigation of cerebellar ataxias. In this review, we discuss the differential diagnosis of the intersection between peripheral nerve and cerebellar involvement, and classify them in accordance with the predominant features. Genetics, clinical features, neuroimaging, and neurophysiologic characteristics are discussed. Furthermore, a diagnostic approach for cerebellar ataxia with neuropathy is proposed according to the different clinical characteristics. This is an Educational and Descriptive review with the aim of medical education for the approach to the patients with cerebellar ataxia and neuropathy. The diagnostic approach to the patient with cerebellar ataxia with neuropathy requires a detailed medical history, phenotyping, characterization of disease progression and family history. Neuroimaging features and the neurophysiological findings play pivotal roles in defining the diagnosis. Establishing an organized classification method for the disorders based on the clinical features may be very helpful, and could be divided as those with predominant cerebellar features, predominant neuropathic feature, or conditions with both cerebellar ataxia and neuropathy. Second, determining the mode of inheritance is critical on cerebellar ataxias: autosomal dominant and recessive cerebellar ataxias, mitochondrial or sporadic types. Third, one must carefully assess neurophysiologic findings in order to better characterize the predominant pattern of involvement: damage location, mechanism of lesion (axonal or demyelinating), motor, sensory or sensory motor compromise, large or small fibers, and autonomic system abnormalities.

Progressive cerebellar atrophy in a patient with complex II and III deficiency and a novel deleterious variant in SDHA: A Counseling Conundrum

BACKGROUND

Complex II is an essential component of the electron transport chain, linking it with the tricarboxylic acid cycle. Its four subunits are encoded in the nuclear genome, and deleterious variants in these genes, including SDHA (OMIM 600857), are associated with a wide range of symptoms including neurological disease, cardiomyopathy, and neoplasia (paraganglioma-pheochromocytomas (PGL/PCC), and gastrointestinal stromal tumors). Deleterious variants of SDHA are most frequently associated with Leigh and Leigh-like syndromes.

METHODS AND RESULTS

Here, we describe a case of a 9-year-old boy with tremor, nystagmus, hypotonia, developmental delay, significant ataxia, and progressive cerebellar atrophy. He was found to have biallelic variants in SDHA, a known pathogenic variant (c.91C>T (p.R31*)), and a variant of unknown significance (c.454G>A (p.E152K)). Deficient activity of complexes II and III was detected in fibroblasts from the patient consistent with a diagnosis of a respiratory chain disorder.

CONCLUSION

We, therefore, consider whether c.454G>A (p.E152K) is, indeed, a pathogenic variant, and what implications it has for family members who carry the same variant.

Reduced Granule Cell Proliferation and Molecular Dysregulation in the Cerebellum of Lysosomal Acid Phosphatase 2 (ACP2) Mutant Mice

Lysosomal acid phosphatase 2 (Acp2) mutant mice (naked-ataxia, nax) have a severe cerebellar cortex defect with a striking reduction in the number of granule cells. Using a combination of in vivo and in vitro immunohistochemistry, Western blotting, BrdU assays, and RT-qPCR, we show downregulation of MYCN and dysregulation of the SHH signaling pathway in the nax cerebellum. MYCN protein expression is significantly reduced at P10, but not at the peak of proliferation at around P6 when the number of granule cells is strikingly reduced in the nax cerebellum. Despite the significant role of the SHH-MycN pathway in granule cell proliferation, our study suggests that a broader molecular pathway and additional mechanisms regulating granule cell development during the clonal expansion period are impaired in the nax cerebellum. In particular, our results indicate that downregulation of the protein synthesis machinery may contribute to the reduced number of granule cells in the nax cerebellum.

Expanding the β-III Spectrin-Associated Phenotypes toward Non-Progressive Congenital Ataxias with Neurodegeneration

(1) Background: A non-progressive congenital ataxia (NPCA) phenotype caused by β-III spectrin (SPTBN2) mutations has emerged, mimicking spinocerebellar ataxia, autosomal recessive type 14 (SCAR14). The pattern of inheritance, however, resembles that of autosomal dominant classical spinocerebellar ataxia type 5 (SCA5). (2) Methods: In-depth phenotyping of two boys studied by a customized gene panel. Candidate variants were sought by structural modeling and protein expression. An extensive review of the literature was conducted in order to better characterize the SPTBN2-associated NPCA. (3) Results: Patients exhibited an NPCA with hypotonia, developmental delay, cerebellar syndrome, and cognitive deficits. Both probands presented with progressive global cerebellar volume loss in consecutive cerebral magnetic resonance imaging studies, characterized by decreasing midsagittal vermis relative diameter measurements. Cortical hyperintensities were observed on fluid-attenuated inversion recovery (FLAIR) images, suggesting a neurodegenerative process. Each patient carried a novel de novo SPTBN2 substitution: c.193A > G (p.K65E) or c.764A > G (p.D255G). Modeling and protein expression revealed that both mutations might be deleterious. (4) Conclusions: The reported findings contribute to a better understanding of the SPTBN2-associated phenotype. The mutations may preclude proper structural organization of the actin spectrin-based membrane skeleton, which, in turn, is responsible for the underlying disease mechanism.

Anti-contactin-associated protein-like 2 antibody-associated cerebellar ataxia: A case report and literature review

The spectrum of anti-contactin-associated protein-like 2 (CASPR2) antibody-associated disease is expanding and the involvement of cerebellum was reported in the past few years. We report a 45-year-old male with chronically progressive cerebellar ataxia. CASPR2 antibodies were detected in his serum and cerebellar atrophy was observed on MRI. His symptoms improved prominently with steroids and intravenous immunoglobulins. 23 cases with CASPR2 antibodies and cerebellar ataxia were identified from previous publications. Most of patients showed acute or subacute onset with other typical presentations of anti-CASPR2 antibody-associated disease, such as limbic encephalitis. Immunotherapy was effective in the majority of patients.

Ataxic phenotype and neurodegeneration are triggered by the impairment of chaperone-mediated autophagy in cerebellar neurons

AIMS

Chaperone-mediated autophagy (CMA) is a pathway involved in the autophagy lysosome protein degradation system. CMA has attracted attention as a contributing factor to neurodegenerative diseases since it participates in the degradation of disease-causing proteins. We previously showed that CMA is generally impaired in cells expressing the proteins causing spinocerebellar ataxias (SCAs). Therefore, we investigated the effect of CMA impairment on motor function and the neural survival of cerebellar neurons using the micro RNA (miRNA)-mediated knockdown of lysosome-associated protein 2A (LAMP2A), a CMA-related protein.

METHODS

We injected adeno-associated virus serotype 9 vectors, which express green fluorescent protein (GFP) and miRNA (negative control miRNA or LAMP2A miRNA) under neuron-specific synapsin I promoter, into cerebellar parenchyma of 4-week-old ICR mice. Motor function of mice was evaluated by beam walking and footprint tests. Immunofluorescence experiments of cerebellar slices were conducted to evaluate histological changes in cerebella.

RESULTS

GFP and miRNA were expressed in interneurons (satellite cells and basket cells) in molecular layers and granule cells in the cerebellar cortices, but not in cerebellar Purkinje cells. LAMP2A knockdown in cerebellar neurons triggered progressive motor impairment, prominent loss of cerebellar Purkinje cells, interneurons, granule cells at the late stage, and astrogliosis and microgliosis from the early stage.

CONCLUSIONS

CMA impairment in cerebellar interneurons and granule cells triggers the progressive ataxic phenotype, gliosis and the subsequent degeneration of cerebellar neurons, including Purkinje cells. Our present findings strongly suggest that CMA impairment is related to the pathogenesis of various SCAs.

Association of A Novel Splice Site Mutation in P/Q-Type Calcium Channels with Childhood Epilepsy and Late-Onset Slowly Progressive Non-Episodic Cerebellar Ataxia

Episodic ataxia type 2 (EA2) is characterized by paroxysmal attacks of ataxia with typical onset in childhood or early adolescence. The disease is associated with mutations in the voltage-gated calcium channel alpha 1A subunit (Cav2.1) that is encoded by the CACNA1A gene. However, previously unrecognized atypical symptoms and the genetic overlap existing between EA2, spinocerebellar ataxia type 6, familial hemiplegic migraine type 1, and other neurological diseases blur the genotype/phenotype correlations, making a differential diagnosis difficult to formulate correctly and delaying early therapeutic intervention. Here we report a new clinical phenotype of a CACNA1A-associated disease characterized by absence epilepsy occurring during childhood. However, much later in life the patient displayed non-episodic, slowly progressive gait ataxia. Gene panel sequencing for hereditary ataxias led to the identification of a novel heterozygous CACNA1A mutation (c.1913 + 2T > G), altering the donor splice site of intron 14. This genetic defect was predicted to result in an in-frame deletion removing 44 amino acids from the voltage-gated calcium channel Cav2.1. An RT-PCR analysis of cDNA derived from patient skin fibroblasts confirmed the skipping of the entire exon 14. Furthermore, two-electrode voltage-clamp recordings performed from Xenopus laevis oocytes expressing a wild-type versus mutant channel showed that the genetic defect caused a complete loss of channel function. This represents the first description of distinct clinical manifestations that remarkably expand the genetic and phenotypic spectrum of CACNA1A-related diseases and should be considered for an early diagnosis and effective therapeutic intervention.

Structural Characterization of Carbonic Anhydrase VIII and Effects of Missense Single Nucleotide Variations to Protein Structure and Function

Human carbonic anhydrase 8 (CA-VIII) is an acatalytic isoform of the α -CA family. Though the protein cannot hydrate CO2, CA-VIII is essential for calcium (Ca2+) homeostasis within the body, and achieves this by allosterically inhibiting the binding of inositol 1,4,5-triphosphate (IP3) to the IP3 receptor type 1 (ITPR1) protein. However, the mechanism of interaction of CA-VIII to ITPR1 is not well understood. In addition, functional defects to CA-VIII due to non-synonymous single nucleotide polymorphisms (nsSNVs) result in Ca2+ dysregulation and the development of the phenotypes such as cerebellar ataxia, mental retardation and disequilibrium syndrome 3 (CAMRQ3). The pathogenesis of CAMRQ3 is also not well understood. The structure and function of CA-VIII was characterised, and pathogenesis of CAMRQ3 investigated. Structural and functional characterisation of CA-VIII was conducted through SiteMap and CPORT to identify potential binding site residues. The effects of four pathogenic nsSNVs, S100A, S100P, G162R and R237Q, and two benign S100L and E109D variants on CA-VIII structure and function was then investigated using molecular dynamics (MD) simulations, dynamic cross correlation (DCC) and dynamic residue network (DRN) analysis. SiteMap and CPORT analyses identified 38 unique CA-VIII residues that could potentially bind to ITPR1. MD analysis revealed less conformational sampling within the variant proteins and highlighted potential increases to variant protein rigidity. Dynamic cross correlation (DCC) showed that wild-type (WT) protein residue motion is predominately anti-correlated, with variant proteins showing no correlation to greater residue correlation. DRN revealed variant-associated increases to the accessibility of the N-terminal binding site residues, which could have implications for associations with ITPR1, and further highlighted differences to the mechanism of benign and pathogenic variants. SNV presence is associated with a reduction to the usage of Trp37 in all variants, which has implications for CA-VIII stability. The differences to variant mechanisms can be further investigated to understand pathogenesis of CAMRQ3, enhancing precision medicine-related studies into CA-VIII.

Infantile-Onset Syndromic Cerebellar Ataxia and CACNA1G Mutations

BACKGROUND

Congenital ataxias associated with cerebellar atrophy are clinically heterogeneous conditions with a variable age of onset and a diverse molecular basis. The hypothesis-free approach of genomic sequencing has led to the discovery of new genes implicated in these disorders and the identification of unexpected genotype-phenotype correlations. Although a recurrent heterozygous mutation (p.Arg1715His) in CACNA1G is known to cause adult-onset spinocerebellar ataxia 42 (SCA42*616795), gain-of-function mutations in this gene have recently been identified by whole exome sequencing (WES) in four children with cerebellar atrophy and ataxia, psychomotor delay, and other variable features.

METHODS

We describe four children from unrelated families with cerebellar anomalies on magnetic resonance imaging (atrophy or hypoplasia of the cerebellar vermis), hypertonia, psychomotor and speech delay, severe intellectual disability, ophthalmologic features and peculiar dysmorphic traits. All patients underwent a trio-based WES analysis. Clinical records were used to characterize the clinical profile of this newly recognized disorder.

RESULTS

Two previously reported de novo disease-causing mutations in CACNA1G (c.2881G>A, p.Ala961Thr and c.4591A>G, p.Met1531Val) were identified in these patients, providing further evidence of the specific impact of these variants. All four patients exhibit distinctive dysmorphic and ectodermal features which overlap those of the previously reported patients, allowing us to define the major features characterizing this homogeneous neurodevelopmental syndromic disorder associated with upregulated CACNA1G function.

CONCLUSION

Our findings confirm the specific association between a narrow spectrum of missense mutations in CACNA1G and a novel syndrome with infantile-onset cerebellar ataxiaand provide a dysmorphologic delineation of this novel neurodevelopmental trait.

Brain MRI of multiple system atrophy of cerebellar type: a prospective study with implications for diagnosis criteria

AIM

The second consensus statement for the diagnosis of multiple system atrophy type cerebellar (MSA-C) includes pons and middle cerebellar peduncle (MCP) atrophy as MRI features. However, other MRI abnormalities such as MCP hyperintensity, hot cross bun sign (HCB), putaminal hypointensity and hyperintense putaminal rim have been described.

OBJECTIVES

To evaluate, in patients with sporadic late-onset cerebellar ataxia (SLOCA), the discriminative value of several MRI features for the diagnosis of MSA-C, to follow their evolution during the course of MSA-C, and to search for correlations between these MRI features and clinical signs.

METHODS

Consecutive patients referred for SLOCA underwent comprehensive clinical evaluation and laboratory investigations, brain MRI, DaTscan and a 1-year follow-up.

RESULTS

Among 80 patients, 26 had MSA-C, 22 another diagnosis, and 32 no diagnosis at the end of the follow-up. At baseline, MCP hyperintensity and HCB were more frequent in patients finally diagnosed with MSA-C than in other patients with SLOCA (p < 0.0001), and had the highest specificity (98.5%) and positive predictive value (91.7%) for the diagnosis of MSA-C, compared to all other MRI signs. The most relevant MRI sequence regarding HCB sign was the T2-proton density (DP) weighted. All MRI features were more frequent with disease duration. No correlation was found between any MRI feature and neither clinical data, nor dopaminergic neuronal loss (p = 0.5008), except between vermis atrophy and UPDRSIII score.

CONCLUSION

MCP hyperintensity and HCB sign should be added into the list of additional features of possible MSA-C. MRI signal abnormalities suggestive of MSA-C should be searched for in suitable sequence.

Bioinformatics-Based Identification of Expanded Repeats: A Non-reference Intronic Pentamer Expansion in RFC1 Causes CANVAS

Genomic technologies such as next-generation sequencing (NGS) are revolutionizing molecular diagnostics and clinical medicine. However, these approaches have proven inefficient at identifying pathogenic repeat expansions. Here, we apply a collection of bioinformatics tools that can be utilized to identify either known or novel expanded repeat sequences in NGS data. We performed genetic studies of a cohort of 35 individuals from 22 families with a clinical diagnosis of cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS). Analysis of whole-genome sequence (WGS) data with five independent algorithms identified a recessively inherited intronic repeat expansion [(AAGGG)exp] in the gene encoding Replication Factor C1 (RFC1). This motif, not reported in the reference sequence, localized to an Alu element and replaced the reference (AAAAG)11 short tandem repeat. Genetic analyses confirmed the pathogenic expansion in 18 of 22 CANVAS-affected families and identified a core ancestral haplotype, estimated to have arisen in Europe more than twenty-five thousand years ago. WGS of the four RFC1-negative CANVAS-affected families identified plausible variants in three, with genomic re-diagnosis of SCA3, spastic ataxia of the Charlevoix-Saguenay type, and SCA45. This study identified the genetic basis of CANVAS and demonstrated that these improved bioinformatics tools increase the diagnostic utility of WGS to determine the genetic basis of a heterogeneous group of clinically overlapping neurogenetic disorders.

A global analysis of IFT-A function reveals specialization for transport of membrane-associated proteins into cilia

Intraflagellar transport (IFT), which is essential for the formation and function of cilia in most organisms, is the trafficking of IFT trains (i.e. assemblies of IFT particles) that carry cargo within the cilium. Defects in IFT cause several human diseases. IFT trains contain the complexes IFT-A and IFT-B. To dissect the functions of these complexes, we studied a Chlamydomonas mutant that is null for the IFT-A protein IFT140. The mutation had no effect on IFT-B but destabilized IFT-A, preventing flagella assembly. Therefore, IFT-A assembly requires IFT140. Truncated IFT140, which lacks the N-terminal WD repeats of the protein, partially rescued IFT and supported formation of half-length flagella that contained normal levels of IFT-B but greatly reduced amounts of IFT-A. The axonemes of these flagella had normal ultrastructure and, as investigated by SDS-PAGE, normal composition. However, composition of the flagellar 'membrane+matrix' was abnormal. Analysis of the latter fraction by mass spectrometry revealed decreases in small GTPases, lipid-anchored proteins and cell signaling proteins. Thus, IFT-A is specialized for the import of membrane-associated proteins. Abnormal levels of the latter are likely to account for the multiple phenotypes of patients with defects in IFT140.This article has an associated First Person interview with the first author of the paper.

Clinical and molecular studies in two new cases of ARSACS

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset neurodevelopmental disorder characterized by the association of spastic ataxia and sensorimotor neuropathy. Additional features include retinal changes and cognitive impairment. Today, next-generation sequencing (NGS) techniques are allowing the rapid identification of a growing number of missense variants, even in less typical forms of the disease, but the pathogenic significance of these changes is often difficult to establish on the basis of classic bioinformatics criteria and genotype/phenotype correlations. Herein, we describe two novel cases of missense mutations in SACS. The two individuals were identified during the genetic screening of a large cohort of patients with inherited ataxias. We discuss how protein studies and specialized ophthalmological investigations could represent useful pointers for the interpretation of genetic data. Combination of these tools with NGS for rapid genotyping might help to identify new true ARSACS cases.

Immune-mediated Cerebellar Ataxias: Practical Guidelines and Therapeutic Challenges

Immune-mediated cerebellar ataxias (IMCAs), a clinical entity reported for the first time in the 1980s, include gluten ataxia (GA), paraneoplastic cerebellar degenerations (PCDs), antiglutamate decarboxylase 65 (GAD) antibody-associated cerebellar ataxia, post-infectious cerebellitis, and opsoclonus myoclonus syndrome (OMS). These IMCAs share common features with regard to therapeutic approaches. When certain factors trigger immune processes, elimination of the antigen( s) becomes a priority: e.g., gluten-free diet in GA and surgical excision of the primary tumor in PCDs. Furthermore, various immunotherapeutic modalities (e.g., steroids, immunoglobulins, plasmapheresis, immunosuppressants, rituximab) should be considered alone or in combination to prevent the progression of the IMCAs. There is no evidence of significant differences in terms of response and prognosis among the various types of immunotherapies. Treatment introduced at an early stage, when CAs or cerebellar atrophy is mild, is associated with better prognosis. Preservation of the "cerebellar reserve" is necessary for the improvement of CAs and resilience of the cerebellar networks. In this regard, we emphasize the therapeutic principle of "Time is Cerebellum" in IMCAs.

Quantitative Assessment of Syllabic Timing Deficits in Ataxic Dysarthria

Parametric analysis of Cerebellar Dysarthria (CD) may be valuable and more informative compared to its clinical assessment. A quantifiable estimation of the timing deficits in repeated syllabic utterance is described in the current study. Thirty-five individuals were diagnosed with cerebellar ataxia to varying degrees and twenty-six age-matched healthy controls were recruited. To automatically detect the local maxima of each syllable in the recorded speech files, a topographic prominence incorporated concept is designed. Subsequently, four acoustic features and eight corresponding parametric measurements are extracted to identify articulatory deficits in ataxic dysarthria. A comparative study on the behaviour of these measures for dysarthric and non-dysarthric subjects is presented in this paper. The results are further explored using a dimensionreduction tool (Principal Component Analysis) to emphasize variation and bring out the strongest discriminating patterns in our feature dataset.

XRCC1 mutation is associated with PARP1 hyperactivation and cerebellar ataxia

XRCC1 is a molecular scaffold protein that assembles multi-protein complexes involved in DNA single-strand break repair. Here we show that biallelic mutations in the human XRCC1 gene are associated with ocular motor apraxia, axonal neuropathy, and progressive cerebellar ataxia. Cells from a patient with mutations in XRCC1 exhibited not only reduced rates of single-strand break repair but also elevated levels of protein ADP-ribosylation. This latter phenotype is recapitulated in a related syndrome caused by mutations in the XRCC1 partner protein PNKP and implicates hyperactivation of poly(ADP-ribose) polymerase/s as a cause of cerebellar ataxia. Indeed, remarkably, genetic deletion of Parp1 rescued normal cerebellar ADP-ribose levels and reduced the loss of cerebellar neurons and ataxia in Xrcc1-defective mice, identifying a molecular mechanism by which endogenous single-strand breaks trigger neuropathology. Collectively, these data establish the importance of XRCC1 protein complexes for normal neurological function and identify PARP1 as a therapeutic target in DNA strand break repair-defective disease.

Late onset cerebellar degeneration in a middle-aged cat

Cerebellar degeneration (abiotrophy) (CD) is a spontaneous and accelerated degeneration of one or several mature cerebellar neuronal cell populations and has been described in many domestic animals, especially in dogs, with numerous breed-related cases. In cats, CD is mentioned as a rare sporadic entity. Late onset CDs are exceptionally uncommon and only two cases are reported in young adults, both aged 18 months. This report describes clinical and pathological findings of a late onset feline CD in a 9-year-old male Persian cat. The cat was presented with a history of progressive ataxia lasting 2 years. Neurological examination revealed severe neurological deficits such as generalised and severe ataxia, hypermetria in all four limbs, and bilateral absence of menace response. The lesion was diffusely localised in cerebellum. On gross pathology, the cerebellum appeared of normal size and shape and kidneys were characterised by mild hyperaemia. Histologically, lesions were limited to the cerebellum and kidneys. In the cerebellum, all cerebellar folia of both hemispheres and the vermis were affected. Changes were characterised by severe and diffuse loss of Purkinje cells, loss of cellularity in the granular layer, mild astrogliosis associated with moderate hypertrophy of Bergmann's glia. Immunohistochemistry for feline parvovirus antigen revealed a negative result. Renal lesions consisted of chronic fibrosis associated with chronic interstitial nephritis. CD is a rare disease and occurs commonly in puppies or young animals, who are clinically normal at birth and usually develop neurological signs within a few weeks or months after birth. This report represents the first case of CD in a middle-aged cat.

Location of lesion determines motor vs. cognitive consequences in patients with cerebellar stroke

Cerebellar lesions can cause motor deficits and/or the cerebellar cognitive affective syndrome (CCAS; Schmahmann's syndrome). We used voxel-based lesion-symptom mapping to test the hypothesis that the cerebellar motor syndrome results from anterior lobe damage whereas lesions in the posterolateral cerebellum produce the CCAS. Eighteen patients with isolated cerebellar stroke (13 males, 5 females; 20-66 years old) were evaluated using measures of ataxia and neurocognitive ability. Patients showed a wide range of motor and cognitive performance, from normal to severely impaired; individual deficits varied according to lesion location within the cerebellum. Patients with damage to cerebellar lobules III-VI had worse ataxia scores: as predicted, the cerebellar motor syndrome resulted from lesions involving the anterior cerebellum. Poorer performance on fine motor tasks was associated primarily with strokes affecting the anterior lobe extending into lobule VI, with right-handed finger tapping and peg-placement associated with damage to the right cerebellum, and left-handed finger tapping associated with left cerebellar damage. Patients with the CCAS in the absence of cerebellar motor syndrome had damage to posterior lobe regions, with lesions leading to significantly poorer scores on language (e.g. right Crus I and II extending through IX), spatial (bilateral Crus I, Crus II, and right lobule VIII), and executive function measures (lobules VII-VIII). These data reveal clinically significant functional regions underpinning movement and cognition in the cerebellum, with a broad anterior-posterior distinction. Motor and cognitive outcomes following cerebellar damage appear to reflect the disruption of different cerebro-cerebellar motor and cognitive loops.

Disruption of an EAAT-Mediated Chloride Channel in a Drosophila Model of Ataxia

Patients with Type 6 episodic ataxia (EA6) have mutations of the excitatory amino acid transporter EAAT1 (also known as GLAST), but the underlying pathophysiological mechanism for EA6 is not known. EAAT1 is a glutamate transporter expressed by astrocytes and other glia, and it serves dual function as an anion channel. One EA6-associated mutation is a P>R substitution (EAAT1(P>R)) that in transfected cells has a reduced rate of glutamate transport and an abnormal anion conductance. We expressed this EAAT1(P>R) mutation in glial cells of Drosophila larvae and found that these larvae exhibit episodic paralysis, and their astrocytes poorly infiltrate the CNS neuropil. These defects are not seen in Eaat1-null mutants, and so they cannot be explained by loss of glutamate transport. We instead explored the role of the abnormal anion conductance of the EAAT1(P>R) mutation, and to do this we expressed chloride cotransporters in astrocytes. Like the EAAT1(P>R) mutation, the chloride-extruding K(+)-Cl(-) cotransporter KccB also caused astroglial malformation and paralysis, supporting the idea that the EAAT1(P>R) mutation causes abnormal chloride flow from CNS glia. In contrast, the Na(+)-K(+)-Cl(-) cotransporter Ncc69, which normally allows chloride into cells, rescued the effects of the EAAT1(P>R) mutation. Together, our results indicate that the cytopathology and episodic paralysis in our Drosophila EA6 model stem from a gain-of-function chloride channelopathy of glial cells.

SIGNIFICANCE STATEMENT

We studied a mutation found in episodic ataxia of the dual-function glutamate transporter/anion channel EAAT1, and discovered it caused malformation of astrocytes and episodes of paralysis in a Drosophila model. These effects were mimicked by a chloride-extruding cotransporter and were rescued by restoring chloride homeostasis to glial cells with a Na(+)-K(+)-2Cl(-) cotransporter. Our findings reveal a new pathophysiological mechanism in which astrocyte cytopathology and neural circuit dysfunction arise via disruption of the ancillary function of EAAT1 as a chloride channel. In some cases, this mechanism might also be important for neurological diseases related to episodic ataxia, such as hemiplegia, migraine, and epilepsy.

A Restricted Repertoire of De Novo Mutations in ITPR1 Cause Gillespie Syndrome with Evidence for Dominant-Negative Effect

Gillespie syndrome (GS) is characterized by bilateral iris hypoplasia, congenital hypotonia, non-progressive ataxia, and progressive cerebellar atrophy. Trio-based exome sequencing identified de novo mutations in ITPR1 in three unrelated individuals with GS recruited to the Deciphering Developmental Disorders study. Whole-exome or targeted sequence analysis identified plausible disease-causing ITPR1 mutations in 10/10 additional GS-affected individuals. These ultra-rare protein-altering variants affected only three residues in ITPR1: Glu2094 missense (one de novo, one co-segregating), Gly2539 missense (five de novo, one inheritance uncertain), and Lys2596 in-frame deletion (four de novo). No clinical or radiological differences were evident between individuals with different mutations. ITPR1 encodes an inositol 1,4,5-triphosphate-responsive calcium channel. The homo-tetrameric structure has been solved by cryoelectron microscopy. Using estimations of the degree of structural change induced by known recessive- and dominant-negative mutations in other disease-associated multimeric channels, we developed a generalizable computational approach to indicate the likely mutational mechanism. This analysis supports a dominant-negative mechanism for GS variants in ITPR1. In GS-derived lymphoblastoid cell lines (LCLs), the proportion of ITPR1-positive cells using immunofluorescence was significantly higher in mutant than control LCLs, consistent with an abnormality of nuclear calcium signaling feedback control. Super-resolution imaging supports the existence of an ITPR1-lined nucleoplasmic reticulum. Mice with Itpr1 heterozygous null mutations showed no major iris defects. Purkinje cells of the cerebellum appear to be the most sensitive to impaired ITPR1 function in humans. Iris hypoplasia is likely to result from either complete loss of ITPR1 activity or structure-specific disruption of multimeric interactions.

Disruptive SCYL1 Mutations Underlie a Syndrome Characterized by Recurrent Episodes of Liver Failure, Peripheral Neuropathy, Cerebellar Atrophy, and Ataxia

Hereditary ataxias comprise a group of genetically heterogeneous disorders characterized by clinically variable cerebellar dysfunction and accompanied by involvement of other organ systems. The molecular underpinnings for many of these diseases are widely unknown. Previously, we discovered the disruption of Scyl1 as the molecular basis of the mouse mutant mdf, which is affected by neurogenic muscular atrophy, progressive gait ataxia with tremor, cerebellar vermis atrophy, and optic-nerve thinning. Here, we report on three human individuals, from two unrelated families, who presented with recurrent episodes of acute liver failure in early infancy and are affected by cerebellar vermis atrophy, ataxia, and peripheral neuropathy. By whole-exome sequencing, compound-heterozygous mutations within SCYL1 were identified in all affected individuals. We further show that in SCYL1-deficient human fibroblasts, the Golgi apparatus is massively enlarged, which is in line with the concept that SCYL1 regulates Golgi integrity. Thus, our findings define SCYL1 mutations as the genetic cause of a human hepatocerebellar neuropathy syndrome.

Alkaline Ceramidase 3 Deficiency Results in Purkinje Cell Degeneration and Cerebellar Ataxia Due to Dyshomeostasis of Sphingolipids in the Brain

Dyshomeostasis of both ceramides and sphingosine-1-phosphate (S1P) in the brain has been implicated in aging-associated neurodegenerative disorders in humans. However, mechanisms that maintain the homeostasis of these bioactive sphingolipids in the brain remain unclear. Mouse alkaline ceramidase 3 (Acer3), which preferentially catalyzes the hydrolysis of C_18:1-ceramide, a major unsaturated long-chain ceramide species in the brain, is upregulated with age in the mouse brain. Acer3 knockout causes an age-dependent accumulation of various ceramides and C_18:1-monohexosylceramide and abolishes the age-related increase in the levels of sphingosine and S1P in the brain; thereby resulting in Purkinje cell degeneration in the cerebellum and deficits in motor coordination and balance. Our results indicate that Acer3 plays critically protective roles in controlling the homeostasis of various sphingolipids, including ceramides, sphingosine, S1P, and certain complex sphingolipids in the brain and protects Purkinje cells from premature degeneration.

Bioactive sphingolipids, such as ceramides and sphingosine-1-phosphates, have been implicated in neurodegenerative diseases. However, it remains unclear as to how the homeostasis of these bioactive lipids is sustained. Alkaline ceramidase 3 (ACER3) catalyzes the hydrolysis of saturated long-chain ceramides (C_18:1-ceramide and C_20:1-ceramide) to generate sphingosine (SPH), which is phosphorylated to form sphingosine-1-phosphate (S1P). In this study we found that Acer3 is upregulated with age in the mouse brain and blocking Acer3 upregulation elevates the levels of ceramides while reducing S1P levels in the brain, thereby resulting in Purkinje cell loss and cerebellar ataxia. This study not only offers novel insights into the role for the homeostasis of ceramides and their metabolites in regulating normal aging of the cerebellum, but also provides a useful genetic tool to dissect the mechanism by which an aberrant accumulation of ceramides results in age-related neurological disorders.

Visualization of Active Glucocerebrosidase in Rodent Brain with High Spatial Resolution following In Situ Labeling with Fluorescent Activity Based Probes

Gaucher disease is characterized by lysosomal accumulation of glucosylceramide due to deficient activity of lysosomal glucocerebrosidase (GBA). In cells, glucosylceramide is also degraded outside lysosomes by the enzyme glucosylceramidase 2 (GBA2) of which inherited deficiency is associated with ataxias. The interest in GBA and glucosylceramide metabolism in the brain has grown following the notion that mutations in the GBA gene impose a risk factor for motor disorders such as α-synucleinopathies. We earlier developed a β-glucopyranosyl-configured cyclophellitol-epoxide type activity based probe (ABP) allowing in vivo and in vitro visualization of active molecules of GBA with high spatial resolution. Labeling occurs through covalent linkage of the ABP to the catalytic nucleophile residue in the enzyme pocket. Here, we describe a method to visualize active GBA molecules in rat brain slices using in vivo labeling. Brain areas related to motor control, like the basal ganglia and motor related structures in the brainstem, show a high content of active GBA. We also developed a β-glucopyranosyl cyclophellitol-aziridine ABP allowing in situ labeling of GBA2. Labeled GBA2 in brain areas can be identified and quantified upon gel electrophoresis. The distribution of active GBA2 markedly differs from that of GBA, being highest in the cerebellar cortex. The histological findings with ABP labeling were confirmed by biochemical analysis of isolated brain areas. In conclusion, ABPs offer sensitive tools to visualize active GBA and to study the distribution of GBA2 in the brain and thus may find application to establish the role of these enzymes in neurodegenerative disease conditions such as α-synucleinopathies and cerebellar ataxia.

'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 2: Anti-PKC-gamma, anti-GluR-delta2, anti-Ca/ARHGAP26 and anti-VGCC

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa head antibodies' due their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects, and provides a summary and outlook.

'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa-head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

Large-scale mass spectrometry imaging investigation of consequences of cortical spreading depression in a transgenic mouse model of migraine

Cortical spreading depression (CSD) is the electrophysiological correlate of migraine aura. Transgenic mice carrying the R192Q missense mutation in the Cacna1a gene, which in patients causes familial hemiplegic migraine type 1 (FHM1), exhibit increased propensity to CSD. Herein, mass spectrometry imaging (MSI) was applied for the first time to an animal cohort of transgenic and wild type mice to study the biomolecular changes following CSD in the brain. Ninety-six coronal brain sections from 32 mice were analyzed by MALDI-MSI. All MSI datasets were registered to the Allen Brain Atlas reference atlas of the mouse brain so that the molecular signatures of distinct brain regions could be compared. A number of metabolites and peptides showed substantial changes in the brain associated with CSD. Among those, different mass spectral features showed significant (t-test, P < 0.05) changes in the cortex, 146 and 377 Da, and in the thalamus, 1820 and 1834 Da, of the CSD-affected hemisphere of FHM1 R192Q mice. Our findings reveal CSD- and genotype-specific molecular changes in the brain of FHM1 transgenic mice that may further our understanding about the role of CSD in migraine pathophysiology. The results also demonstrate the utility of aligning MSI datasets to a common reference atlas for large-scale MSI investigations.

Change in the cortical complexity of spinocerebellar ataxia type 3 appears earlier than clinical symptoms

Patients with spinocerebellar ataxia type 3 (SCA3) have exhibited cerebral cortical involvement and various mental deficits in previous studies. Clinically, conventional measurements, such as the Mini-Mental State Examination (MMSE) and electroencephalography (EEG), are insensitive to cerebral cortical involvement and mental deficits associated with SCA3, particularly at the early stage of the disease. We applied a three-dimensional fractal dimension (3D-FD) method, which can be used to quantify the shape complexity of cortical folding, in assessing cortical degeneration. We evaluated 48 genetically confirmed SCA3 patients by employing clinical scales and magnetic resonance imaging and using 50 healthy participants as a control group. According to the Scale for the Assessment and Rating of Ataxia (SARA), the SCA3 patients were diagnosed with cortical dysfunction in the cerebellar cortex; however, no significant difference in the cerebral cortex was observed according to the patients’ MMSE ratings. Using the 3D-FD method, we determined that cortical involvement was more extensive than involvement of traditional olivopontocerebellar regions and the corticocerebellar system. Moreover, the significant correlation between decreased 3D-FD values and disease duration may indicate atrophy of the cerebellar cortex and cerebral cortex in SCA3 patients. The change of the cerebral complexity in the SCA3 patients can be detected throughout the disease duration, especially it becomes substantial at the late stage of the disease. Furthermore, we determined that atrophy of the cerebral cortex may occur earlier than changes in MMSE scores and EEG signals.

A deletion in the VLDLR gene in Eurasier dogs with cerebellar hypoplasia resembling a Dandy-Walker-like malformation (DWLM)

Dandy-Walker-like malformation (DWLM) is the result of aberrant brain development and mainly characterized by cerebellar hypoplasia. DWLM affected dogs display a non-progressive cerebellar ataxia. Several DWLM cases were recently observed in the Eurasier dog breed, which strongly suggested a monogenic autosomal recessive inheritance in this breed. We performed a genome-wide association study (GWAS) with 9 cases and 11 controls and found the best association of DWLM with markers on chromosome 1. Subsequent homozygosity mapping confirmed that all 9 cases were homozygous for a shared haplotype in this region, which delineated a critical interval of 3.35 Mb. We sequenced the genome of an affected Eurasier and compared it with the Boxer reference genome and 47 control genomes of dogs from other breeds. This analysis revealed 4 private non-synonymous variants in the critical interval of the affected Eurasier. We genotyped these variants in additional dogs and found perfect association for only one of these variants, a single base deletion in the VLDLR gene encoding the very low density lipoprotein receptor. This variant, VLDLR:c.1713delC is predicted to cause a frameshift and premature stop codon (p.W572Gfs*10). Variants in the VLDLR gene have been shown to cause congenital cerebellar ataxia and mental retardation in human patients and Vldlr knockout mice also display an ataxia phenotype. Our combined genetic data together with the functional knowledge on the VLDLR gene from other species thus strongly suggest that VLDLR:c.1713delC is indeed causing DWLM in Eurasier dogs.

Inferior cerebellar hypoplasia resembling a Dandy-Walker-like malformation in purebred Eurasier dogs with familial non-progressive ataxia: a retrospective and prospective clinical cohort study

Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5 – 6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance.

Dynamic Cerebrospinal Fluid Flow on MRI in Cortical Cerebellar Atrophy and Multiple System Atrophy-cerebellar Type

OBJECTIVE

The purpose of this study was to examine a new MRI technology, dynamic cerebrospinal fluid (CSF) flow, to examine sporadic cerebellar ataxia patients with cortical cerebellar atrophy (CCA) and multiple system atrophy-cerebellar type (MSA-C).

METHODS

Nine CCA patients (3 men and 6 women; mean age: 64.2±6.9 years) and 31 MSA-C patients (13 men and 18 women; mean age: 62.7±6.8 years) were examined by a dynamic CSF flow analysis. All CSF flow data were evaluated by phase contrast-MRI using a 1.5T MRI scanner. The CSF flow was calculated by 15 images in the equidistant MRI sequence which was taken through a cardiac cycle.

RESULTS

Compared with the CCA patients, the absolute values of the mean velocity of the MSA-C patients were significantly reduced at time points 5 (CCA, 0.24±0.14 cm/s; MSA-C, 0.13±0.11 cm/s; (*) p<0.05) and 13 (CCA, -0.60±0.37 cm/s; MSA-C, -0.31±0.17 cm/s; (**) p<0.01). Significant correlations in Spearman's rank correlation coefficient were also found in MSA-C patients between the disease duration and the difference between the maximum and minimum velocities (Vheight) (r=-0.429, (*) p<0.05), the minimum velocity of the CSF (Vmin) (r=0.486, (**) p<0.01) or the length of the minor axis of the pons (r=-0.529, (**) p<0.01). The linear regressions between the disease duration and Vheight or Vmin revealed a significant strong correlation only in the MSA-C patients.

CONCLUSION

The present CSF flow study showed for the first time that Vheight and Vmin revealed good correlations with the disease duration in the MSA-C patients. Furthermore, the velocity of the prepontine CSF flow tended to decrease in the MSA-C patients compared with the CCA patients, suggesting that this particular CSF flow analysis may be a new surrogate marker for differentiating both types of cerebellar ataxia.

Adult-onset autosomal recessive ataxia associated with neuronal ceroid lipofuscinosis type 5 gene (CLN5) mutations

Autosomal recessive inherited ataxias are a growing group of genetic disorders. We report two Italian siblings presenting in their mid-50s with difficulty in walking, dysarthria and progressive cognitive decline. Visual loss, ascribed to glaucoma, manifested a few years before the other symptoms. Brain MRI showed severe cerebellar atrophy, prevalent in the vermis, with marked cortical atrophy of both hemispheres. Exome sequencing identified a novel homozygous mutation (c.935G > A;p.Ser312Asn) in the ceroid neuronal lipofuscinosis type 5 gene (CLN5). Bioinformatics predictions and in vitro studies showed that the mutation was deleterious and likely affects ER-lysosome protein trafficking. Our findings support CLN5 hypomorphic mutations cause autosomal recessive cerebellar ataxia, confirming other reports showing CLN mutations are associated with adult-onset neurodegenerative disorders. We suggest CLN genes should be considered in the molecular analyses of patients presenting with adult-onset autosomal recessive cerebellar ataxia.

Mutations in SNX14 cause a distinctive autosomal-recessive cerebellar ataxia and intellectual disability syndrome

Intellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum.

Paraneoplastic cerebellar ataxia associated with anti-Hu antibodies and benign ganglioneuroma

We describe a case of cerebellar ataxia associated with anti-Hu antibodies and benign ganglioneuroma. A 28-year-old woman developed progressive ataxia with hyporeflexia at the age of 19. Brain MRI showed progressive cerebellar atrophy. Neurophysiological studies, screening of immune-mediated ataxias, oncological markers, vitamin E and genetic tests for spinocerebellar ataxia types 1,2,3, Friedreich ataxia and POLG1 were negative. Anti-Hu antibodies were positive in Western blot and indirect immunofluorescence (1:640). Total-body computed tomography revealed a mediastinum mass; the histological diagnosis was maturing ganglioneuroma. Immunohistochemistry showed a mild reaction between the tumor and the patient's serum, and no reaction between the tumor and control serum. After surgery, serum anti-Hu titer decreased, while ataxic symptoms initially worsened and then stabilized. Ganglioneuroma is a benign tumor, usually derived from the maturation of a neuroblastoma. The benign histology and the presence of anti-Hu antibodies could be related to the positive oncological prognosis and to the slow clinical course mimicking a degenerative ataxia.

Automatic method for thalamus parcellation using multi-modal feature classification

Segmentation and parcellation of the thalamus is an important step in providing volumetric assessment of the impact of disease n brain structures. Conventionally, segmentation is carried out on T1-weighted magnetic resonance (MR) images and nuclear parcellation using diffusion weighted MR images. We present the first fully automatic method that incorporates both tissue contrasts and several derived fea-fractional anisotrophy, fiber orientation from the 5D Knutsson representation of the principal eigenvectors, and connectivity between the thalamus and the cortical lobes, as features. Combining these multiple information sources allows us to identify discriminating dimensions and thus parcellate the thalamic nuclei. A hierarchical random forest framework with a multidimensional feature per voxel, first distinguishes thalamus from background, and then separates each group of thalamic nuclei. Using a leave one out cross-validation on 12 subjects we have a mean Dice score of 0.805 and 0.799 for the left and right thalami, respectively. We also report overlap for the thalamic nuclear groups.

Quantitative evaluation of cerebellar ataxia based on pathological patterns of the muscle activities

Quantitative evaluation of cerebellar ataxia is crucial for precise evaluation of cerebellar diseases. In particular, it is essential to capture anomaly of the causal motor commands as well as the resultant movement for the ataxia. In this paper, we propose a new method to make a quantitative evaluation of the cerebellar ataxia based on EMG signals. As an experimental task, we asked subjects to perform step-tracking wrist movements with a manipulandum, and recorded wrist joint movements and muscle activities of four wrist prime movers with surface electrodes. The subjects included fourteen patients with cerebellar diseases and thirteen normal controls. We succeeded to extract two parameters from the EMG signals of the four wrist prime movers, which characterize the pathological patterns of muscle activities for the cerebellar ataxia, Total Co-contraction Level (TCL) and Directionality of Muscle Activity (DMA). We found that the two parameters were useful to characterize pathological patterns of muscle activities in cerebellar ataxia. Consequently, it is expected that our proposed method is useful not only in tracking condition of cerebellar patients but also in evaluating the effects of a treatment or neuro-rehabilitation aiming at the normalization of motor commands.

[Peculiarities of ataxic disorders in patients with acute isolated cerebellar infarction]

In this article we showed clinic-neurological and neurovisualizative investigation of 20 patients with acute isolated cerebellar infarction and taking into account frequency of symptoms of the cerebellar ataxia peculiarities of ataxic disorders were determined according to involved anatomic structures and arterial territories of the cerebellum.