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See detailMitochondrial Mechanisms of LRRK2 G2019S Penetrance
Delcambre, Sylvie UL; Ghelfi, Jenny UL; Ouzren, Nassima et al

in Frontiers in Neurology (2020)

Several mutations in leucine-rich repeat kinase-2 (LRRK2) have been associated with Parkinson’s disease (PD). The most common substitution, G2019S, interferes with LRRK2 kinase activity, which is ... [more ▼]

Several mutations in leucine-rich repeat kinase-2 (LRRK2) have been associated with Parkinson’s disease (PD). The most common substitution, G2019S, interferes with LRRK2 kinase activity, which is regulated by autophosphorylation. Yet, the penetrance of this gain-of-function mutation is incomplete, and thus far, few factors have been correlated with disease status in carriers. This includes (i) LRRK2 autophosphorylation in urinary exosomes, (ii) serum levels of the antioxidant urate, and (iii) abundance of mitochondrial DNA (mtDNA) transcription-associated 7S DNA. In light of a mechanistic link between LRRK2 kinase activity and mtDNA lesion formation, we previously investigated mtDNA integrity in fibroblasts from manifesting (LRRK2+/PD+) and non-manifesting carriers (LRRK2+/PD−) of the G2019S mutation as well as from aged-matched controls. In our published study, mtDNA major arc deletions correlated with PD status, with manifesting carriers presenting the highest levels. In keeping with these findings, we now further explored mitochondrial features in fibroblasts derived from LRRK2+/PD+ (n = 10), LRRK2+/PD− (n = 21), and control (n = 10) individuals. In agreement with an accumulation of mtDNA major arc deletions, we also detected reduced NADH dehydrogenase activity in the LRRK2+/PD+ group. Moreover, in affected G2019S carriers, we observed elevated mitochondrial mass and mtDNA copy numbers as well as increased expression of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates antioxidant signaling. Taken together, these results implicate mtDNA dyshomeostasis—possibly as a consequence of impaired mitophagy—in the penetrance of LRRK2-associated PD. Our findings are a step forward in the pursuit of unveiling markers that will allow monitoring of disease progression of LRRK2 mutation carriers [less ▲]

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See detailBidirectional Relation Between Parkinson’s Disease and Glioblastoma Multiforme
Mencke, Pauline UL; Hanss, Zoé; Boussaad, Ibrahim UL et al

in Frontiers in Neurology (2020)

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See detailGenetic Architecture of Parkinson's Disease in the Indian Population: Harnessing Genetic Diversity to Address Critical Gaps in Parkinson's Disease Research.
Rajan, Roopa; Divya, K. P.; Kandadai, Rukmini Mridula et al

in Frontiers in neurology (2020), 11

Over the past two decades, our understanding of Parkinson's disease (PD) has been gleaned from the discoveries made in familial and/or sporadic forms of PD in the Caucasian population. The transferability ... [more ▼]

Over the past two decades, our understanding of Parkinson's disease (PD) has been gleaned from the discoveries made in familial and/or sporadic forms of PD in the Caucasian population. The transferability and the clinical utility of genetic discoveries to other ethnically diverse populations are unknown. The Indian population has been under-represented in PD research. The Genetic Architecture of PD in India (GAP-India) project aims to develop one of the largest clinical/genomic bio-bank for PD in India. Specifically, GAP-India project aims to: (1) develop a pan-Indian deeply phenotyped clinical repository of Indian PD patients; (2) perform whole-genome sequencing in 500 PD samples to catalog Indian genetic variability and to develop an Indian PD map for the scientific community; (3) perform a genome-wide association study to identify novel loci for PD and (4) develop a user-friendly web-portal to disseminate results for the scientific community. Our "hub-spoke" model follows an integrative approach to develop a pan-Indian outreach to develop a comprehensive cohort for PD research in India. The alignment of standard operating procedures for recruiting patients and collecting biospecimens with international standards ensures harmonization of data/bio-specimen collection at the beginning and also ensures stringent quality control parameters for sample processing. Data sharing and protection policies follow the guidelines established by local and national authorities.We are currently in the recruitment phase targeting recruitment of 10,200 PD patients and 10,200 healthy volunteers by the end of 2020. GAP-India project after its completion will fill a critical gap that exists in PD research and will contribute a comprehensive genetic catalog of the Indian PD population to identify novel targets for PD. [less ▲]

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See detailThe Emerging Role of RHOT1/Miro1 in the Pathogenesis of Parkinson's Disease.
Grossmann, Dajana; Berenguer-Escuder, Clara; Chemla, Axel UL et al

in Frontiers in neurology (2020), 11

The expected increase in prevalence of Parkinson's disease (PD) as the most common neurodegenerative movement disorder over the next years underscores the need for a better understanding of the underlying ... [more ▼]

The expected increase in prevalence of Parkinson's disease (PD) as the most common neurodegenerative movement disorder over the next years underscores the need for a better understanding of the underlying molecular pathogenesis. Here, first insights provided by genetics over the last two decades, such as dysfunction of molecular and organellar quality control, are described. The mechanisms involved relate to impaired intracellular calcium homeostasis and mitochondrial dynamics, which are tightly linked to the cross talk between the endoplasmic reticulum (ER) and mitochondria. A number of proteins related to monogenic forms of PD have been mapped to these pathways, i.e., PINK1, Parkin, LRRK2, and α-synuclein. Recently, Miro1 was identified as an important player, as several studies linked Miro1 to mitochondrial quality control by PINK1/Parkin-mediated mitophagy and mitochondrial transport. Moreover, Miro1 is an important regulator of mitochondria-ER contact sites (MERCs), where it acts as a sensor for cytosolic calcium levels. The involvement of Miro1 in the pathogenesis of PD was recently confirmed by genetic evidence based on the first PD patients with heterozygous mutations in RHOT1/Miro1. Patient-based cellular models from RHOT1/Miro1 mutation carriers showed impaired calcium homeostasis, structural alterations of MERCs, and increased mitochondrial clearance. To account for the emerging role of Miro1, we present a comprehensive overview focusing on the role of this protein in PD-related neurodegeneration and highlighting new developments in our understanding of Miro1, which provide new avenues for neuroprotective therapies for PD patients. [less ▲]

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See detailContributing Factors and Evolution of Impulse Control Disorder in the Luxembourg Parkinson Cohort.
Binck, Sylvia UL; Pauly, Claire UL; Vaillant, Michel et al

in Frontiers in neurology (2020), 11

Background: To establish the frequency of impulse control disorder (ICD) in Parkinson's disease (PD). Methods: Within the Luxembourg Parkinson's Study, PD patients were evaluated for ICD presence (score ≥ ... [more ▼]

Background: To establish the frequency of impulse control disorder (ICD) in Parkinson's disease (PD). Methods: Within the Luxembourg Parkinson's Study, PD patients were evaluated for ICD presence (score ≥ 1 on MDS-UPDRS I item 1.6), use of dopamine agonists (DA) and other medications. Results: 470 patients were enrolled. Among 217 patients without DA use, 6.9% scored positive for ICD, vs. 15.4% among 253 patients with DA use (p = 0.005). The regression analysis showed that age at PD diagnosis had only a minor impact on ICD occurrence, while there was no influence by gender or co-medications. The longitudinal study over 2 years in 156 patients demonstrated increasing ICD frequency in DA users (p = 0.005). Conclusion: This large and non-interventional study confirms that PD patients with DA treatment show higher frequency of ICD than patients without DA use. It newly demonstrates that ICD can develop independently from age, gender, or co-medications. [less ▲]

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See detailMultilingual Validation of the First French Version of Munich Dysphagia Test-Parkinson's Disease (MDT-PD) in the Luxembourg Parkinson's Study
Simons, Janine UL; Vaillant, Michel; Hipp Epouse D'amico, Géraldine UL et al

in Frontiers in Neurology (2019)

The Munich Dysphagia Test for Parkinson's disease (MDT-PD) was initially developed and validated in the German population as a highly sensitive and specific self-reported screening questionnaire to detect ... [more ▼]

The Munich Dysphagia Test for Parkinson's disease (MDT-PD) was initially developed and validated in the German population as a highly sensitive and specific self-reported screening questionnaire to detect early oropharyngeal symptoms and aspiration risk in patients with idiopathic Parkinson's disease (iPD). In order to make this tool accessible for prevention in the French speaking populations worldwide, we performed the first French translation and provide a linguistic and psychometric validation in the unique multilingual environment of the Luxembourg Parkinson's Study. [less ▲]

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See detailLong-Term Effect of GPi-DBS in a Patient With Generalized Dystonia Due to GLUT1 Deficiency Syndrome.
Hanci, Idil; Kamm, Christoph; Scholten, Marlieke et al

in Frontiers in neurology (2018), 9

Treatment outcomes from pallidal deep brain stimulation are highly heterogeneous reflecting the phenotypic and etiologic spectrum of dystonia. Treatment stratification to neurostimulation therapy ... [more ▼]

Treatment outcomes from pallidal deep brain stimulation are highly heterogeneous reflecting the phenotypic and etiologic spectrum of dystonia. Treatment stratification to neurostimulation therapy primarily relies on the phenotypic motor presentation; however, etiology including genetic factors are increasingly recognized as modifiers of treatment outcomes. Here, we describe a 53 year-old female patient with a progressive generalized dystonia since age 25. The patient underwent deep brain stimulation of the globus pallidus internus (GPi-DBS) at age 44. Since the clinical phenotype included mobile choreo-dystonic features, we expected favorable therapeutic outcome from GPi-DBS. Although mobile dystonia components were slightly improved in the long-term outcome from GPi-DBS the overall therapeutic response 9 years from implantation was limited when comparing "stimulation off" and "stimulation on" despite of proper electrode localization and sufficient stimulation programming. In order to further understand the reason for this limited motor symptom response, we aimed to clarify the etiology of generalized dystonia in this patient. Genetic testing identified a novel heterozygous pathogenic SLC2A1 mutation as cause of glucose transporter type 1 deficiency syndrome (GLUT1-DS). This case report presents the first outcome of GPi-DBS in a patient with GLUT1-DS, and suggests that genotype relations may increasingly complement phenotype-based therapy stratification of GPi-DBS in dystonia. [less ▲]

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See detailEffects of Subthalamic and Nigral Stimulation on Gait Kinematics in Parkinson's Disease.
Scholten, Marlieke; Klemt, Johannes; Heilbronn, Melanie et al

in Frontiers in neurology (2017), 8

Conventional subthalamic deep brain stimulation for Parkinson's disease (PD) presumably modulates the spatial component of gait. However, temporal dysregulation of gait is one of the factors that is ... [more ▼]

Conventional subthalamic deep brain stimulation for Parkinson's disease (PD) presumably modulates the spatial component of gait. However, temporal dysregulation of gait is one of the factors that is tightly associated with freezing of gait (FOG). Temporal locomotor integration may be modulated differentially at distinct levels of the basal ganglia. Owing to its specific descending brainstem projections, stimulation of the substantia nigra pars reticulata (SNr) area might modulate spatial and temporal parameters of gait differentially compared to standard subthalamic nucleus (STN) stimulation. Here, we aimed to characterize the differential effect of STN or SNr stimulation on kinematic gait parameters. We analyzed biomechanical parameters during unconstrained over ground walking in 12 PD patients with subthalamic deep brain stimulation and FOG. Patients performed walking in three therapeutic conditions: (i) Off stimulation, (ii) STN stimulation (alone), and (iii) SNr stimulation (alone). SNr stimulation was achieved by stimulating the most caudal contact of the electrode. We recorded gait using three sensors (each containing a tri-axial accelerometer, gyroscope, and magnetometer) attached on both left and right ankle, and to the lumbar spine. STN stimulation improved both the spatial features (stride length, stride length variability) and the temporal parameters of gait. SNr stimulation improved temporal parameters of gait (swing time asymmetry). Correlation analysis suggested that patients with more medial localization of the SNr contact associated with a stronger regularization of gait. These results suggest that SNr stimulation might support temporal regularization of gait integration. [less ▲]

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