Adult-Onset Ataxia With Neuropathy and White Matter Abnormalities Due to a Novel SAMD9L Variant
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ABSTRACT:
SUBMITTER: Paucar M
PROVIDER: S-EPMC8554712 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:To report a novel mutation in the gene EIF2B3 responsible for a late-onset form of vanishing white matter disease.Case report.University teaching hospital.A 29-year-old pregnant woman with a history of premature ovarian failure and hemiplegic migraines presented with a 10-week history of progressive confusion and headaches. Magnetic resonance imaging of the brain revealed a diffuse leukoencephalopathy.Sequencing of the exons and intron boundaries of EIF2B3 uncovered 2 missense mutations: c.260C>T(p.Ala87Val) and c.272G>A(p.Arg91His). To our knowledge,the latter missense mutation has never been previously reported.This is the second report of adult-onset vanishing white matter disease due to mutations in EIF2B3 and the first report of the c.272G>A (p.Arg91His) missense mutation.
| S-EPMC4154510 | biostudies-literature
Project description:BackgroundSpinocerebellar ataxia syndromes presenting in adulthood have a broad range of causes, and despite extensive investigation remain undiagnosed in up to ∼50% cases. Mutations in the mitochondrially encoded MTATP6 gene typically cause infantile-onset Leigh syndrome and, occasionally, have onset later in childhood. The authors report two families with onset of ataxia in adulthood (with pyramidal dysfunction and/or peripheral neuropathy variably present), who are clinically indistinguishable from other spinocerebellar ataxia patients.MethodsGenetic screening study of the MTATP6 gene in 64 pedigrees with unexplained ataxia, and case series of two families who had MTATP6 mutations.ResultsThree pedigrees had mutations in MTATP6, two of which have not been reported previously and are detailed in this report. These families had the m.9185T>C and m.9035T>C mutations, respectively, which have not previously been associated with adult-onset cerebellar syndromes. Other investigations including muscle biopsy and respiratory chain enzyme activity were non-specific or normal.ConclusionsMTATP6 sequencing should be considered in the workup of undiagnosed ataxia, even if other investigations do not suggest a mitochondrial DNA disorder.
| S-EPMC4034166 | biostudies-literature
Project description:Mitochondrial dysfunction plays a key role in the pathophysiology of neurodegenerative disorders such as ataxia and Parkinson's disease. We describe an extended Belgian pedigree where seven individuals presented with adult-onset cerebellar ataxia, axonal peripheral ataxic neuropathy, and tremor, in variable combination with parkinsonism, seizures, cognitive decline, and ophthalmoplegia. We sought to identify the underlying molecular etiology and characterize the mitochondrial pathophysiology of this neurological syndrome.Clinical, neurophysiological, and neuroradiological evaluations were conducted. Patient muscle and cultured fibroblasts underwent extensive analyses to assess mitochondrial function. Genetic studies including genome-wide sequencing were conducted.Hallmarks of mitochondrial dysfunction were present in patients' tissues including ultrastructural anomalies of mitochondria, mosaic cytochrome c oxidase deficiency, and multiple mtDNA deletions. We identified a splice acceptor variant in POLG2, c.970-1G>C, segregating with disease in this family and associated with a concomitant decrease in levels of POLG2 protein in patient cells.This work extends the clinical spectrum of POLG2 deficiency to include an overwhelming, adult-onset neurological syndrome that includes cerebellar syndrome, peripheral neuropathy, tremor, and parkinsonism. We therefore suggest to include POLG2 sequencing in the evaluation of ataxia and sensory neuropathy in adults, especially when it is accompanied by tremor or parkinsonism with white matter disease. The demonstration that deletions of mtDNA resulting from autosomal-dominant POLG2 variant lead to a monogenic neurodegenerative multicomponent syndrome provides further evidence for a major role of mitochondrial dysfunction in the pathomechanism of nonsyndromic forms of the component neurodegenerative disorders.
| S-EPMC5221457 | biostudies-literature
Project description:The recognition, diagnosis and management of mild traumatic brain injuries are difficult and confusing. It is unclear how the severity and number of injuries sustained relate to brain injuries, such as diffuse axonal injury, diffuse vascular injury and progressive neurodegeneration. Advances in neuroimaging techniques enable the investigation of neuropathologies associated with acute and long-term effects of injury. Head injuries are the most commonly reported injury seen during professional rugby. There is increased vigilance for the immediate effects of these injuries in matches, but there has been surprisingly little research investigating the longer-term effects of rugby participation. Here, we present a longitudinal observational study investigating the relationship of exposure to rugby participation and sub-acute head injuries in professional adult male and female rugby union and league players using advanced MRI. Diffusion tensor imaging and susceptibility weighted imaging was used to assess white matter structure and evidence of axonal and diffuse vascular injury. We also studied changes in brain structure over time using Jacobian Determinant statistics extracted from serial volumetric imaging. We tested 41 male and 3 female adult elite rugby players, of whom 21 attended study visits after a head injury, alongside 32 non-sporting controls, 15 non-collision-sport athletic controls and 16 longitudinally assessed controls. Eighteen rugby players participated in the longitudinal arm of the study, with a second visit at least 6 months after their first scan. Neuroimaging evidence of either axonal injury or diffuse vascular injury was present in 23% (10/44) of players. In the non-acutely injured group of rugby players, abnormalities of fractional anisotropy and other diffusion measures were seen. In contrast, non-collision-sport athletic controls were not classified as showing abnormalities. A group level contrast also showed evidence of sub-acute injury using diffusion tensor imaging in rugby players. Examination of longitudinal imaging revealed unexpected reductions in white matter volume in the elite rugby players studied. These changes were not related to self-reported head injury history or neuropsychological test scores and might indicate excess neurodegeneration in white matter tracts affected by injury. Taken together, our findings suggest an association of participation in elite adult rugby with changes in brain structure. Further well-designed large-scale studies are needed to understand the impact of both repeated sports-related head impacts and head injuries on brain structure, and to clarify whether the abnormalities we have observed are related to an increased risk of neurodegenerative disease and impaired neurocognitive function following elite rugby participation.
| S-EPMC8381344 | biostudies-literature
Project description: Not available
| S-EPMC8054956 | biostudies-literature
Project description:To characterize white matter abnormalities in adolescents with early-onset schizophrenia (EOS) relative to 3 comparison groups (adolescents at clinical high risk for developing schizophrenia [CHR], adolescents with cannabis use disorder [CUD], and healthy controls [HC]), and to identify neurocognitive correlates of white matter abnormalities in EOS.We used diffusion tensor imaging and tractography methods to examine fractional anisotropy (FA) of the cingulum bundle, superior longitudinal fasciculus, corticospinal tract (CST), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), and uncinate fasciculus in adolescents with EOS (n = 55), CHR (n = 21), CUD (n = 31), and HC (n = 55). FA in tracts that were significantly altered in EOS was correlated with neurocognitive performance.EOS and CHR groups had significantly lower FA than HC in 4 tracts, namely, bilateral CST, left ILF, and left IFOF. CUD had lower FA than HC in left IFOF. Lower FA in left IFOF and left ILF predicted worse neurocognitive performance in EOS.This study identified white matter abnormalities of the left ILF and left IFOF as possible biomarkers of vulnerability for developing schizophrenia. Lower FA in these tracts may disrupt functioning of ventral visual and language streams, producing domain-specific neurocognitive deficits that interfere with higher-order cognitive abilities.
| S-EPMC3977613 | biostudies-literature
Project description:Misophonia is a condition in which specific ordinary sounds provoke disproportionately strong negative affect and physiological arousal. Evidence for neurobiological abnormalities underlying misophonia is scarce. Since many psychiatric disorders show white matter (WM) abnormalities, we tested for both macro and micro-structural WM differences between misophonia patients and healthy controls. We collected T1-weighted and diffusion-weighted magnetic resonance images from 24 patients and 25 matched controls. We tested for group differences in WM volume using whole-brain voxel-based morphometry and used the significant voxels from this analysis as seeds for probabilistic tractography. After calculation of diffusion tensors, we compared group means for fractional anisotropy, mean diffusivity, and directional diffusivities, and applied tract-based spatial statistics for voxel-wise comparison. Compared to controls, patients had greater left-hemispheric WM volumes in the inferior fronto-occipital fasciculus, anterior thalamic radiation, and body of the corpus callosum connecting bilateral superior frontal gyri. Patients also had lower averaged radial and mean diffusivities and voxel-wise comparison indicated large and widespread clusters of lower mean diffusivity. We found both macro and microstructural WM abnormalities in our misophonia sample, suggesting misophonia symptomatology is associated with WM alterations. These biological alterations may be related to differences in social-emotional processing, particularly recognition of facial affect, and to attention for affective information.
| S-EPMC8405911 | biostudies-literature
Project description:Background: Charcot-Marie-Tooth (CMT) is the most frequent group of inherited neuropathies and includes several heterogeneous phenotypes. Over 80 causative genes have been described so far. Variants in the microrchidia family CW-type zinc finger 2 (MORC2) gene have been described in several axonal polyneuropathy (CMT2) patients with childhood or adult onset. Occasionally more complex phenotypes with delayed milestones, severe hypotonia, intellectual disability, dystonic postures, pyramidal signs, and neuroimaging abnormalities have been reported. Case Presentation: We report on a patient with a de novo MORC2 gene variant (c.1181A>G p.Tyr394Cys) with a history of developmental delay, axial hypotonia, progressive gait disorder with dystonic features, and intentional tremor. At the age of 8 years, he showed bilateral pyramidal signs (clonus, increased tendon reflexes, and Babinski sign) and bilateral pes cavus. The first neuroimaging performed at the age of 3 years demonstrated white matter abnormalities in the posterior periventricular zone, in the frontal lobes bilaterally and at the midbrain, stable during childhood and adolescence. Nerve conduction studies (NCS) were negative until the age of 15 years, when a sensory axonal neuropathy appeared. The association between pyramidal signs and neuropathy due to the MORC2 gene variant is increasingly being highlighted, although a neuroradiological correlate is evident only in about half of the cases. Longitudinal nerve conduction velocity (NCV) are helpful to identify late-onset features and provide useful information for diagnosis in patients with rare neurogenetic disorders. Conclusions: Characterization of complex neurological disorders is important to delineate the expanding phenotypic spectrum of MORC2-related disease, to confirm if possible the pathogenicity of the variants and to deepen the genotype-phenotype correlation.
| S-EPMC8493287 | biostudies-literature
Project description:BackgroundBiallelic STUB1 variants are a well-established cause of autosomal-recessive early-onset multisystemic ataxia (SCAR16). Evidence for STUB1 variants causing autosomal-dominant ataxia (SCA48) so far largely relies on segregation data in larger families. Presenting the first de novo occurrence of a heterozygous STUB1 variant, we here present additional qualitative evidence for STUB1-disease as an autosomal-dominant disorder.MethodsWhole exome sequencing on an index patient with sporadic early-onset ataxia, followed by Sanger sequencing in all family members, was used to identify causative variants as well as to rule out alternative genetic hits and intronic STUB1 variants. STUB1 mRNA and protein levels in PBMCs in all family members were analysed using qRT-PCR and Western Blot.ResultsA previously unreported start-lost loss-of-function variant c.3G>A in the start codon of STUB1 was identified in the index case, occurring de novo and without evidence for a second (potentially missed) variant (e.g., intronic or copy number) in STUB1. The patient showed an early adult-onset multisystemic ataxia complicated by spastic gait disorder, distal myoclonus and cognitive dysfunction, thus closely mirroring the systems affected in autosomal-recessive STUB1-associated disease. In line with the predicted start-lost effect of the variant, functional investigations demonstrated markedly reduced STUB1 protein expression in PBMCs, whereas mRNA levels were intact.ConclusionDe novo occurrence of the loss-of-function STUB1 variant in our case with multisystemic ataxia provides a qualitatively additional line of evidence for STUB1-disease as an autosomal-dominant disorder, in which the same neurological systems are affected as in its autosomal-recessive counterpart. Moreover, this finding adds support for loss-of-function as a mechanism underlying autosomal-dominant STUB1-disease, thus mirroring its autosomal-recessive counterpart also in terms of the underlying mutational mechanism.
| S-EPMC8463406 | biostudies-literature
Project description: Not available
| S-EPMC7296852 | biostudies-literature