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American Journal of Medical Genetics.... Jul 2023Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare neurodegenerative disorders characterized by a wide phenotypic range including severe motor and...
Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare neurodegenerative disorders characterized by a wide phenotypic range including severe motor and cognitive impairments, microcephaly, distinctive facial features, and other features according to the type. Several classes of PCH1 have been linked to mutations in the evolutionarily conserved RNA exosome complex that consists of nine subunits (EXOSC1 to EXOSC9) and facilitates the degradation and processing of cytoplasmic and nuclear RNA from the 3' end. Only a single individual with an EXOSC1 mutation was reported with clinical features of PCH type 1 (PCH1F). Here, we report a 3-month-old female with PCH and additional clinical features not previously reported to be associated with PCH1, including dilated cardiomyopathy. On assessment, failure to thrive, microcephaly, distinctive facial features, and bluish sclera, were noted. Whole-exome sequencing was performed and revealed a novel homozygous missense variant c.547C > T (p.Arg183Trp) in the EXOSC1 gene. Functional studies in a budding yeast model that expresses the human EXOSC1 variant Arg183Trp show a slow-growth phenotype, whereas the previously identified PCH1F allele EXOSC1-Ser35Leu is lethal, indicating impaired exosome function for both of these variants. The protein levels of both EXOSC1 variants are reduced compared with wild-type when expressed in budding yeast. Herein, we ascertain the second case of PCH associated with a EXOSC1 variant that causes defects in RNA exosome function and provide a model organism system to distinguish between benign and pathogenic variants in EXOSC1.
Topics: Humans; Female; Infant; Microcephaly; Cerebellar Diseases; Olivopontocerebellar Atrophies; Mutation; Nervous System Malformations; Exosome Multienzyme Ribonuclease Complex; RNA-Binding Proteins
PubMed: 37024942
DOI: 10.1002/ajmg.a.63198 -
Cells Feb 2023Multiple system atrophy (MSA) is a debilitating movement disorder with unknown etiology. Patients present characteristic parkinsonism and/or cerebellar dysfunction in... (Review)
Review
Multiple system atrophy (MSA) is a debilitating movement disorder with unknown etiology. Patients present characteristic parkinsonism and/or cerebellar dysfunction in the clinical phase, resulting from progressive deterioration in the nigrostriatal and olivopontocerebellar regions. MSA patients have a prodromal phase subsequent to the insidious onset of neuropathology. Therefore, understanding the early pathological events is important in determining the pathogenesis, which will assist with developing disease-modifying therapy. Although the definite diagnosis of MSA relies on the positive post-mortem finding of oligodendroglial inclusions composed of α-synuclein, only recently has MSA been verified as an oligodendrogliopathy with secondary neuronal degeneration. We review up-to-date knowledge of human oligodendrocyte lineage cells and their association with α-synuclein, and discuss the postulated mechanisms of how oligodendrogliopathy develops, oligodendrocyte progenitor cells as the potential origins of the toxic seeds of α-synuclein, and the possible networks through which oligodendrogliopathy induces neuronal loss. Our insights will shed new light on the research directions for future MSA studies.
Topics: Humans; alpha-Synuclein; Cell Lineage; Multiple System Atrophy; Neurons; Parkinsonian Disorders
PubMed: 36899876
DOI: 10.3390/cells12050739 -
Brain Pathology (Zurich, Switzerland) May 2023The pathological hallmark of multiple system atrophy (MSA) is aberrant accumulation of phosphorylated α-synuclein in oligodendrocytes, forming glial cytoplasmic...
Early and extensive alterations of glial connexins, distal oligodendrogliopathy type demyelination, and nodal/paranodal pathology are characteristic of multiple system atrophy.
The pathological hallmark of multiple system atrophy (MSA) is aberrant accumulation of phosphorylated α-synuclein in oligodendrocytes, forming glial cytoplasmic inclusions (GCIs). Extensive demyelination occurs particularly in the olivopontocerebellar and striatonigral pathways, but its precise mechanism remains elusive. Glial connexins (Cxs), which form gap junction channels between astrocytes and oligodendrocytes, play critical roles in myelin maintenance, and have not been studied in MSA. Therefore, we immunohistochemically investigated glial Cx changes in the cerebellar afferent fibers in 15 autopsied patients with MSA. We classified demyelinating lesions into three stages based on Klüver-Barrera staining: early (Stage I), intermediate (Stage II), and late (Stage III) stages showing subtle, moderate, and severe myelin reduction, respectively. Myelin-associated glycoprotein, but not myelin oligodendrocyte glycoprotein, was preferentially decreased in Stage I, suggesting distal oligodendrogliopathy type demyelination. Accumulation of phosphorylated α-synuclein in oligodendrocytes was frequently seen in Stage I but less frequently observed in Stages II and III. Tubulin polymerization-promoting protein (TPPP/p25α)-positive oligodendrocytes were preserved in Stage I but successively decreased in Stages II and III. Even at Stage I, Cx32 was nearly absent from myelin, despite the relative preservation of other nodal proteins, such as neurofascin, claudin-11/oligodendrocyte-specific protein, and contactin-associated protein 1, which successively decreased in the later stages. Cx32 was re-distributed in the oligodendrocyte cytoplasm and co-localized with GCIs. Cx47 gradually decreased at the oligodendrocyte surface in a stage-dependent manner but was not co-localized with GCIs. Astrocytic Cx43 was down-regulated in Stage I but up-regulated in Stages II and III, reflecting astrogliosis. Cx43/Cx47 gap junctions significantly decreased from Stage I to III. Activated microglia/macrophages and T cells infiltrated in Stage I rather than Stages II and III. Therefore, early and extensive alterations of glial Cxs, particularly Cx32 loss, occur in MSA and may accelerate distal oligodendrogliopathy type demyelination and nodal/paranodal dysfunction through disruption of inter-glial communication.
Topics: Humans; Connexins; Connexin 43; alpha-Synuclein; Multiple System Atrophy; Demyelinating Diseases
PubMed: 36368713
DOI: 10.1111/bpa.13131 -
Biology Jun 2022Multiple-system atrophy (MSA) is primarily an autonomic disorder with parkinsonism or cerebellar ataxia. Clinical diagnosis of MSA at an early stage is challenging...
Multiple-system atrophy (MSA) is primarily an autonomic disorder with parkinsonism or cerebellar ataxia. Clinical diagnosis of MSA at an early stage is challenging because the symptoms change over the course of the disease. Recently, various artificial intelligence-based programs have been developed to improve the diagnostic accuracy of neurodegenerative diseases, but most are limited to the evaluation of diagnostic imaging. In this study, we examined the validity of diagnosis of MSA using a pointwise linear model (deep learning-based method). The goal of the study was to identify features associated with disease differentiation that were found to be important in deep learning. A total of 3377 registered MSA cases from FY2004 to FY2008 were used to train the model. The diagnostic probabilities of SND (striatonigral degeneration), SDS (Shy-Drager syndrome), and OPCA (olivopontocerebellar atrophy) were estimated to be 0.852 ± 0.107, 0.650 ± 0.235, and 0.858 ± 0.270, respectively. In the pointwise linear model used to identify and visualize features involved in individual subtypes, autonomic dysfunction was found to be a more prominent component of SDS compared to SND and OPCA. Similarly, respiratory failure was identified as a characteristic of SDS, dysphagia was identified as a characteristic of SND, and brain-stem atrophy was identified as a characteristic of OPCA.
PubMed: 36101332
DOI: 10.3390/biology11070951 -
Movement Disorders : Official Journal... Oct 2022Multiple System Atrophy is a rare neurodegenerative disease with alpha-synuclein aggregation in glial cytoplasmic inclusions and either...
BACKGROUND
Multiple System Atrophy is a rare neurodegenerative disease with alpha-synuclein aggregation in glial cytoplasmic inclusions and either predominant olivopontocerebellar atrophy or striatonigral degeneration, leading to dysautonomia, parkinsonism, and cerebellar ataxia. One prior genome-wide association study in mainly clinically diagnosed patients with Multiple System Atrophy failed to identify genetic variants predisposing for the disease.
OBJECTIVE
Since the clinical diagnosis of Multiple System Atrophy yields a high rate of misdiagnosis when compared to the neuropathological gold standard, we studied only autopsy-confirmed cases.
METHODS
We studied common genetic variations in Multiple System Atrophy cases (N = 731) and controls (N = 2898).
RESULTS
The most strongly disease-associated markers were rs16859966 on chromosome 3, rs7013955 on chromosome 8, and rs116607983 on chromosome 4 with P-values below 5 × 10 , all of which were supported by at least one additional genotyped and several imputed single nucleotide polymorphisms. The genes closest to the chromosome 3 locus are ZIC1 and ZIC4 encoding the zinc finger proteins of cerebellum 1 and 4 (ZIC1 and ZIC4).
INTERPRETATION
Since mutations of ZIC1 and ZIC4 and paraneoplastic autoantibodies directed against ZIC4 are associated with severe cerebellar dysfunction, we conducted immunohistochemical analyses in brain tissue of the frontal cortex and the cerebellum from 24 Multiple System Atrophy patients. Strong immunohistochemical expression of ZIC4 was detected in a subset of neurons of the dentate nucleus in all healthy controls and in patients with striatonigral degeneration, whereas ZIC4-immunoreactive neurons were significantly reduced inpatients with olivopontocerebellar atrophy. These findings point to a potential ZIC4-mediated vulnerability of neurons in Multiple System Atrophy. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Autoantibodies; Autopsy; Genome-Wide Association Study; Humans; Multiple System Atrophy; Nerve Tissue Proteins; Olivopontocerebellar Atrophies; Striatonigral Degeneration; Transcription Factors; alpha-Synuclein
PubMed: 35997131
DOI: 10.1002/mds.29164 -
Neurotherapeutics : the Journal of the... Jan 2023Multiple system atrophy (MSA) is a rare neurodegenerative disorder with unclear etiology, currently difficult and delayed diagnosis, and rapid progression, leading to... (Review)
Review
Multiple system atrophy (MSA) is a rare neurodegenerative disorder with unclear etiology, currently difficult and delayed diagnosis, and rapid progression, leading to disability and lethality within 6 to 9 years after symptom onset. The neuropathology of MSA classifies the disease in the group of a-synucleinopathies together with Parkinson's disease and other Lewy body disorders, but features specific oligodendroglial inclusions, which are pathognomonic for MSA. MSA has no efficient therapy to date. Development of experimental models is crucial to elucidate the disease mechanisms in progression and to provide a tool for preclinical screening of putative therapies for MSA. In vitro and in vivo models, based on selective neurotoxicity, a-synuclein oligodendroglial overexpression, and strain-specific propagation of a-synuclein fibrils, have been developed, reflecting various facets of MSA pathology. Over the years, the continuous exchange from bench to bedside and backward has been crucial for the advancing of MSA modelling, elucidating MSA pathogenic pathways, and understanding the existing translational gap to successful clinical trials in MSA. The review discusses specifically advantages and limitations of the PLP-a-syn mouse model of MSA, which recapitulates motor and non-motor features of the human disease with underlying striatonigral degeneration, degeneration of autonomic centers, and sensitized olivopontocerebellar system, strikingly mirroring human MSA pathology.
Topics: Animals; Humans; Mice; alpha-Synuclein; Brain; Disease Models, Animal; Mice, Transgenic; Multiple System Atrophy; Neuropathology; Oligodendroglia; Phenotype; Translational Research, Biomedical
PubMed: 35995919
DOI: 10.1007/s13311-022-01287-8 -
American Journal of Human Genetics May 2022Pontocerebellar hypoplasias (PCHs) are congenital disorders characterized by hypoplasia or early atrophy of the cerebellum and brainstem, leading to a very limited motor...
Pontocerebellar hypoplasias (PCHs) are congenital disorders characterized by hypoplasia or early atrophy of the cerebellum and brainstem, leading to a very limited motor and cognitive development. Although over 20 genes have been shown to be mutated in PCHs, a large proportion of affected individuals remains undiagnosed. We describe four families with children presenting with severe neonatal brainstem dysfunction and pronounced deficits in cognitive and motor development associated with four different bi-allelic mutations in PRDM13, including homozygous truncating variants in the most severely affected individuals. Brain MRI and fetopathological examination revealed a PCH-like phenotype, associated with major hypoplasia of inferior olive nuclei and dysplasia of the dentate nucleus. Notably, histopathological examinations highlighted a sparse and disorganized Purkinje cell layer in the cerebellum. PRDM13 encodes a transcriptional repressor known to be critical for neuronal subtypes specification in the mouse retina and spinal cord but had not been implicated, so far, in hindbrain development. snRNA-seq data mining and in situ hybridization in humans show that PRDM13 is expressed at early stages in the progenitors of the cerebellar ventricular zone, which gives rise to cerebellar GABAergic neurons, including Purkinje cells. We also show that loss of function of prdm13 in zebrafish leads to a reduction in Purkinje cells numbers and a complete absence of the inferior olive nuclei. Altogether our data identified bi-allelic mutations in PRDM13 as causing a olivopontocerebellar hypoplasia syndrome and suggest that early deregulations of the transcriptional control of neuronal fate specification could contribute to a significant number of cases.
Topics: Animals; Brain Diseases; Brain Stem; Cerebellum; Developmental Disabilities; Histone-Lysine N-Methyltransferase; Humans; Mice; Mutation; Nervous System Malformations; Neurogenesis; Purkinje Cells; Transcription Factors; Zebrafish
PubMed: 35390279
DOI: 10.1016/j.ajhg.2022.03.010 -
Biomedicines Mar 2022Multiple system atrophy (MSA) is a fatal, rapidly progressing neurodegenerative disease of uncertain etiology, clinically characterized by various combinations of... (Review)
Review
Multiple system atrophy (MSA) is a fatal, rapidly progressing neurodegenerative disease of uncertain etiology, clinically characterized by various combinations of Levodopa unresponsive parkinsonism, cerebellar, autonomic and motor dysfunctions. The morphological hallmark of this α-synucleinopathy is the deposition of aberrant α-synuclein in both glia, mainly oligodendroglia (glial cytoplasmic inclusions /GCIs/) and neurons, associated with glioneuronal degeneration of the striatonigral, olivopontocerebellar and many other neuronal systems. Typical phenotypes are MSA with predominant parkinsonism (MSA-P) and a cerebellar variant (MSA-C) with olivocerebellar atrophy. However, MSA can present with a wider range of clinical and pathological features than previously thought. In addition to rare combined or "mixed" MSA, there is a broad spectrum of atypical MSA variants, such as those with a different age at onset and disease duration, "minimal change" or prodromal forms, MSA variants with Lewy body disease or severe hippocampal pathology, rare forms with an unusual tau pathology or spinal myoclonus, an increasing number of MSA cases with cognitive impairment/dementia, rare familial forms, and questionable conjugal MSA. These variants that do not fit into the current classification of MSA are a major challenge for the diagnosis of this unique proteinopathy. Although the clinical diagnostic accuracy and differential diagnosis of MSA have improved by using combined biomarkers, its distinction from clinically similar extrapyramidal disorders with other pathologies and etiologies may be difficult. These aspects should be taken into consideration when revising the current diagnostic criteria. This appears important given that disease-modifying treatment strategies for this hitherto incurable disorder are under investigation.
PubMed: 35327402
DOI: 10.3390/biomedicines10030599 -
Tomography (Ann Arbor, Mich.) Feb 2022MRI shows the three archetypal patterns of CNS volume loss underlying progressive ataxias in vivo, namely spinal atrophy (SA), cortical cerebellar atrophy (CCA) and... (Review)
Review
MRI shows the three archetypal patterns of CNS volume loss underlying progressive ataxias in vivo, namely spinal atrophy (SA), cortical cerebellar atrophy (CCA) and olivopontocerebellar atrophy (OPCA). The MRI-based CNS atrophy pattern was reviewed in 128 progressive ataxias. A CNS atrophy pattern was identified in 91 conditions: SA in Friedreich's ataxia, CCA in 5 acquired and 72 (24 dominant, 47 recessive,1 X-linked) inherited ataxias, OPCA in Multi-System Atrophy and 12 (9 dominant, 2 recessive,1 X-linked) inherited ataxias. The MRI-based CNS atrophy pattern may be useful for genetic assessment, identification of shared cellular targets, repurposing therapies or the enlargement of drug indications in progressive ataxias.
Topics: Ataxia; Atrophy; Cerebellar Ataxia; Humans; Magnetic Resonance Imaging; Spinocerebellar Degenerations
PubMed: 35202200
DOI: 10.3390/tomography8010035 -
Archivos Argentinos de Pediatria Feb 2022The latest method of next-generation sequencing has allowed the characterization and identification of genetic variants associated to diverse pathologies. In this...
The latest method of next-generation sequencing has allowed the characterization and identification of genetic variants associated to diverse pathologies. In this article, we present the case of female patient with a mutation of the RARS2 gene that encodes the enzyme for arginyl tRNA synthetase for coding of proteins. This genetic alteration manifests in pontocerebellar hypoplasia type 6, with a prevalence of<1/1,000,0000, characterized by a cerebellum and pons that are smaller in size and are associated with severe neurodevelopmental delay. The analysis of the case of this patient provides better knowledge of diseases of genetic origin; specifically, regarding genetic diseases of autosomal recessive patterns of inheritance from non-consanguineous parents. The impact of these studies; specially within the family, social, economic and genetic aspects helps provide a better quality of life for these patients and their family.
Topics: Arginine-tRNA Ligase; Colombia; Consanguinity; Female; Humans; Magnetic Resonance Imaging; Mutation; Parents; Quality of Life
PubMed: 35068129
DOI: 10.5546/aap.2022.e39