Primary Orthostatic Tremor in Adolescence

Tremor is an involuntary rhythmic muscle contraction, which causes a regular oscillation of a part of the body. Orthostatic tremor is a rare neurological movement disorder characterized by unsteadiness while standing that is relieved when sitting, walking, or lying down. Neurological examination of primary orthostatic tremor is reported to be normal. The pathophysiological mechanism of this condition is not entirely unknown. Symptoms usually start in the sixth decade. Clonazepam is widely used as a first-line medication in the treatment. A 14-year-old girl patient was admitted due to tremor activated on standing, absent while seated or lying, and improved by walking or leaning. Her brain magnetic resonance imaging and laboratory workup were normal. Tremor completely disappeared with clonazepam in 10 days. I report a case of primary orthostatic tremor in adolescence.

MLF2 modulates phase separated nuclear envelope condensates that provoke dual proteotoxicity

DYT1 dystonia is a highly debilitating neurological movement disorder arising from mutation in the AAA+ ATPase TorsinA. The hallmark of Torsin dysfunction is nuclear envelope blebbing resulting from defects in nuclear pore complex biogenesis. Whether blebs actively contribute to disease manifestation is presently unknown. We report that FG-nucleoporins in the bleb lumen undergo phase separation and contribute to DYT1 dystonia by provoking two proteotoxic insults. Short-lived ubiquitinated proteins that are normally rapidly degraded in healthy cells partition into the bleb lumen and become stabilized. Additionally, blebs selectively sequester a chaperone network composed of HSP70s and HSP40s. The composition of this chaperone network is altered by the bleb component MLF2. We further demonstrate that MLF2 is a catalyst of phase separation that suppresses the ectopic accumulation of FG-nucleoporins and modulates the selective properties and size of condensates in vitro. Our studies identify unprecedented, dual mechanisms of proteotoxicity in the context of liquid-liquid phase separation with direct implications for our understanding of disease etiology and treatment.

Taakspecifieke focale dystonie bij musici

Task-specific focal dystonia in musicians Task-specific focal dystonia is a neurological movement disorder characterized by involuntary contractions during a specific activity. In musicians, the abnormal movement can occur while playing an instrument or while singing. The muscle contractions are usually painless, but the function of the affected region is disturbed. The clinical picture occurs more in men than in women and is most frequent in pianists or guitarists. The abnormality is usually localized in the fingers, the hands or the entire arm. Drummers can have problems in the lower limbs. Brass and woodwind players can lose control of the lips, tongue or facial muscles. This is called “embouchure dystonia”. Singers suffer from the larynx. The diagnosis is a clinical diagnosis. It is important to observe the musician making music. Outside the musical activity, all tests are normal. Technical examinations can be useful to rule out other diagnoses. The therapy is difficult and often unsatisfactory. In many cases, the disease predicts the end of the musical career.

Gut microbiome and serum metabolome alterations in isolated dystonia

Background Dystonia is a complex neurological movement disorder characterised by involuntary muscle contractions. The relationship between the gut microbiota and isolated dystonia remains poorly explored. Methods We collected faeces and blood samples to study the microbiome and the serum metabolome from a cohort of 57 drug-naïve isolated dystonia patients and 27 age- and environment-matched healthy individuals. We first sequenced the V4 regions of the 16S rDNA gene from all faeces samples. Further, we performed metagenomic sequencing of gut microbiome and non-targeted metabolomics profiling of serum from dystonia patients with significant dysbiosis. Results Gut microbial β-diversity was significantly different, with a more heterogeneous community structure among dystonia individuals than healthy controls, while no difference in α-diversity was found. Gut microbiota in dystonia patients was enriched with Blautia obeum, Dorea longicatena and Eubacterium hallii, but depleted with Bacteroides vulgatus and Bacteroides plebeius. Metagenomic sequencing revealed that genes related to the citrate cycle, vitamin B6 and glycan metabolism were less abundant in dystonia, while genes linked to purine and tryptophan biosynthesis were more abundant. Serum metabolome analysis revealed altered levels of tyrosine and glutamate. The integrative analysis of the gut microbiome and serum metabolomics identified dystonia-associated gut microbial species linked to changes in serum metabolites, reflecting the effect of the gut microbiome on metabolic activity in isolated dystonia. Conclusion This study is the first to reveal gut microbial dysbiosis in dystonia patients. Our findings identified previously unknown links between intestinal microbiota alterations, circulating amino acids and dystonia, providing new insight into the pathogenesis of isolated dystonia.

Stem Cell-Based Therapies for Parkinson Disease

Parkinson disease (PD) is a neurological movement disorder resulting primarily from damage to and degeneration of the nigrostriatal dopaminergic pathway. The pathway consists of neural populations in the substantia nigra that project to the striatum of the brain where they release dopamine. Diagnosis of PD is based on the presence of impaired motor features such as asymmetric or unilateral resting tremor, bradykinesia, and rigidity. Nonmotor features including cognitive impairment, sleep disorders, and autonomic dysfunction are also present. No cure for PD has been discovered, and treatment strategies focus on symptomatic management through restoration of dopaminergic activity. However, proposed cell replacement therapies are promising because midbrain dopaminergic neurons have been shown to restore dopaminergic neurotransmission and functionally rescue the dopamine-depleted striatum. In this review, we summarize our current understanding of the molecular pathogenesis of neurodegeneration in PD and discuss the development of new therapeutic strategies that have led to the initiation of exploratory clinical trials. We focus on the applications of stem cells for the treatment of PD and discuss how stem cell research has contributed to an understanding of PD, predicted the efficacy of novel neuroprotective therapeutics, and highlighted what we believe to be the critical areas for future research.

Whole exome sequencing identifies novel DYT1 dystonia-associated genome variants as potential disease modifiers

Background：DYT1 dystonia is a neurological movement disorder characterized by painful sustained muscle contractions resulting in abnormal twisting and postures. In a subset of patients, it is caused by a loss-of-function mutation (ΔE302/303; or ΔE) in the luminal ATPases associated with various cellular activities (AAA+) protein torsinA encoded by the TOR1A gene. The low penetrance of the ΔE mutation (~30-40%) suggests the existence of unknown genetic modifiers of DYT1 dystonia. Results：To identify these modifiers, we performed whole exome sequencing (WES) of blood leukocyte DNA isolated from two DYT1 dystonia patients, three asymptomatic carriers of the ΔE mutation, and an unaffected adult relative. A total of 264 DYT1 dystonia-associated variants (DYT1 variants) were identified in 195 genes. Consistent with the emerging view of torsinA as an important regulator of the cytoskeleton, endoplasmic reticulum homeostasis, and lipid metabolism, we found DYT1 variants in genes that encode proteins implicated in these processes. Moreover, 40 DYT1 variants were detected in 32 genes associated with neuromuscular and neuropsychiatric disorders. Conclusion： The DYT1 variants described in this work represent exciting new targets for future studies designed to increase our understanding of the pathophysiology and pathogenesis of DYT1 dystonia.

Clinical Spectrum of KCNA1 Mutations: New Insights into Episodic Ataxia and Epilepsy Comorbidity

Mutations in the KCNA1 gene, which encodes voltage-gated Kv1.1 potassium channel α-subunits, cause a variety of human diseases, complicating simple genotype–phenotype correlations in patients. KCNA1 mutations are primarily associated with a rare neurological movement disorder known as episodic ataxia type 1 (EA1). However, some patients have EA1 in combination with epilepsy, whereas others have epilepsy alone. KCNA1 mutations can also cause hypomagnesemia and paroxysmal dyskinesia in rare cases. Why KCNA1 variants are associated with such phenotypic heterogeneity in patients is not yet understood. In this review, literature databases (PubMed) and public genetic archives (dbSNP and ClinVar) were mined for known pathogenic or likely pathogenic mutations in KCNA1 to examine whether patterns exist between mutation type and disease manifestation. Analyses of the 47 deleterious KCNA1 mutations that were identified revealed that epilepsy or seizure-related variants tend to cluster in the S1/S2 transmembrane domains and in the pore region of Kv1.1, whereas EA1-associated variants occur along the whole length of the protein. In addition, insights from animal models of KCNA1 channelopathy were considered, as well as the possible influence of genetic modifiers on disease expressivity and severity. Elucidation of the complex relationship between KCNA1 variants and disease will enable better diagnostic risk assessment and more personalized therapeutic strategies for KCNA1 channelopathy.

Whole exome sequencing identifies novel DYT1 dystonia-associated genome variants as potential disease modifiers

BackgroundDYT1 dystonia is a neurological movement disorder characterized by painful sustained muscle contractions resulting in abnormal twisting and postures. In a subset of patients, it is caused by a loss-of-function mutation (ΔE302/303; or ΔE) in the luminal ATPases associated with various cellular activities (AAA+) protein torsinA encoded by the TOR1A gene. The low penetrance of the ΔE mutation (∼30-40%) suggests the existence of unknown genetic modifiers of DYT1 dystonia.MethodsTo identify these modifiers, we performed whole exome sequencing of blood leukocyte DNA isolated from two DYT1 dystonia patients, three asymptomatic carriers of the ΔE mutation, and an unaffected adult relative.ResultsA total of 264 DYT1 dystonia-associated variants (DYT1 variants) were identified in 195 genes. Consistent with the emerging view of torsinA as an important regulator of the cytoskeleton, endoplasmic reticulum homeostasis, and lipid metabolism, we found DYT1 variants in genes that encode proteins implicated in these processes. Moreover, 40 DYT1 variants were detected in 32 genes associated with neuromuscular and neuropsychiatric disorders.ConclusionThe DYT1 variants described in this work represent exciting new targets for future studies designed to increase our understanding of the pathophysiology and pathogenesis of DYT1 dystonia.

Essential tremor: genetic update

Essential tremor (ET) is a neurological movement disorder characterised by bilateral limb kinetic/postural tremor, with or without tremor in other body parts including head, voice and lower limbs. Since no causative genes for ET have been identified, it is likely that the disorder occurs as a result of complex genetic factors interacting with various cellular and environmental factors that can result in abnormal function of circuitry involving the cerebello–thalamo–cortical pathway. Genetic analyses have uncovered at least 14 loci and 11 genes that are related to ET, as well as various risk or protective genetic factors. Limitations in ET genetic analyses include inconsistent disease definition, small sample size, varied ethnic backgrounds and many other factors that may contribute to paucity of relevant genetic data in ET. Genetic analyses, coupled with functional and animal studies, have led to better insights into possible pathogenic mechanisms underlying ET. These genetic studies may guide the future development of genetic testing and counselling, and specific, pathogenesis-targeted, therapeutic strategies.