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Background: Parkinsonian features have been described in patients harboring variants in nuclear genes encoding for proteins involved in mitochondrial DNA maintenance, such as TWNK.Objectives: The aim was to screen for TWNK variants in an Italian cohort of Parkinson's disease (PD) patients and to assess the occurrence of parkinsonism in patients presenting with TWNK-related autosomal dominant progressive external ophthalmoplegia (TWNK-adPEO).Methods: Genomic DNA of 263 consecutively collected PD patients who underwent diagnostic genetic testing was analyzed with a targeted custom gene panel including TWNK, as well as genes causative of monogenic PD. Genetic and clinical data of 18 TWNK-adPEO patients with parkinsonism were retrospectively analyzed.Results: Six of 263 PD patients (2%), presenting either with isolated PD (n = 4) or in combination with bilateral ptosis (n = 2), carried TWNK likely pathogenic variants. Among 18 TWNK-adPEO patients, 5 (28%) had parkinsonism.Conclusions: We show candidate TWNK variants occurring in PD without PEO. This finding will require further confirmatory studies. © 2022 Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Background: Melanopsin retinal ganglion cell (mRGC)‐mediated pupillary light reflex (PLR) abnormalities have been documented in several neurodegenerative disorders including Parkinson's disease. Overall, isolated rapid eye movement (REM) sleep behavior disorder (iRBD) represents the strongest prodromal risk factor for impending α‐synucleinopathies. Objectives: To quantitatively compare PLR and mRGC‐mediated contribution to PLR in 16 iRBD patients and 16 healthy controls. Methods: iRBD and controls underwent extensive neuro‐ophthalmological evaluation and chromatic pupillometry. In iRBD, PLR metrics were correlated with clinical variables and with additional biomarkers including REM atonia index (RAI), DaTscan, and presence of phosphorylated‐α‐synuclein (p‐α‐syn) deposition in skin biopsy. Results: We documented higher baseline pupil diameter and decreased rod‐transient PLR amplitude in iRBD patients compared to controls. PLR rod‐contribution correlated with RAI. Moreover, only iRBD patients with evidence of p‐α‐syn deposition at skin biopsy showed reduced PLR amplitude compared to controls. Conclusion: The observed PLR abnormalities in iRBD might be considered as potential biomarkers for the risk stratification of phenoconversion of the disease. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to describe the clinical and demographic features of idiopathic non‐task‐specific upper limb dystonia compared with the task‐specific form. Methods: In this retrospective study, adult patients with idiopathic upper limb dystonia, either focal or as part of a segmental/multifocal dystonia, from the Italian Dystonia Registry were enrolled. In patients with focal upper limb dystonia, dystonia spread was estimated by survival analysis. Results: Of the 1522 patients with idiopathic adult‐onset dystonia included in the Italian Dystonia Registry, we identified 182 patients with upper limb dystonia. Non‐task‐specific dystonia was present in 61.5% of enrolled cases. Women predominated among non‐task‐specific patients, whereas men predominated in the task‐specific group. Peak age of upper limb dystonia onset was in the sixth decade in the non‐task‐specific group and in the fourth decade in the task‐specific group. In both groups, upper limb dystonia started as focal dystonia or as part of a segmental dystonia. Segmental onset was more frequent among non‐task‐specific patients, whereas focal onset predominated among task‐specific patients. Dystonic action tremor was more frequent among non‐task‐specific patients. No significant differences between groups emerged in terms of sensory trick frequency, rest tremor, or family history of dystonia. In patients with focal upper limb dystonia, dystonia spread was greater in the non‐task‐specific group. Conclusion: Novel information on upper limb dystonia patients suggests that non‐task‐specific and task‐specific upper limb dystonia have different demographic and clinical features. However, it remains to be determined whether these differences also reflect pathophysiological differences. © 2020 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Background: Somatosensory temporal discrimination threshold is often prolonged in patients with dystonia. Previous evidence suggested that this might be caused by impaired somatosensory processing in the time domain. Here, we tested if other markers of reduced inhibition in the somatosensory system might also contribute to abnormal somatosensory temporal discrimination in dystonia.Methods: Somatosensory temporal discrimination threshold was measured in 19 patients with isolated cervical dystonia and 19 age-matched healthy controls. We evaluated temporal somatosensory inhibition using paired-pulse somatosensory evoked potentials, spatial somatosensory inhibition by measuring the somatosensory evoked potentials interaction between simultaneous stimulation of the digital nerves in thumb and index finger, and Gamma-aminobutyric acid-ergic (GABAergic) sensory inhibition using the early and late components of high-frequency oscillations in digital nerves somatosensory evoked potentials.Results: When compared with healthy controls, dystonic patients had longer somatosensory temporal discrimination thresholds, reduced suppression of cortical and subcortical paired-pulse somatosensory evoked potentials, less spatial inhibition of simultaneous somatosensory evoked potentials, and a smaller area of the early component of the high-frequency oscillations. A logistic regression analysis found that paired pulse suppression of the N20 component at an interstimulus interval of 5 milliseconds and the late component of the high-frequency oscillations were independently related to somatosensory temporal discrimination thresholds. "Dystonia group" was also a predictor of enhanced somatosensory temporal discrimination threshold, indicating a dystonia-specific effect that independently influences this threshold.Conclusions: Increased somatosensory temporal discrimination threshold in dystonia is related to reduced activity of inhibitory circuits within the primary somatosensory cortex. © 2016 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]