scholarly journals Genetic Variants in SNCA and the Risk of Sporadic Parkinson’s Disease and Clinical Outcomes: A Review

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Clarissa Loureiro das Chagas Campêlo ◽  
Regina Helena Silva
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Environmental Factors ◽  
Clinical Outcomes ◽  
Association Studies ◽  
Clinical Aspects ◽  
Genome Wide Association Studies ◽  
Snca Gene ◽  
Increased Risk

There is increasing evidence of the contribution of genetic susceptibility to the etiology of Parkinson’s disease (PD). Genetic variations in the SNCA gene are well established by linkage and genome-wide association studies. Positive associations of single nucleotide polymorphisms (SNPs) in SNCA and increased risk for PD were found. However, the role of SNCA variants in individual traits or phenotypes of PD is unknown. Here, we reviewed the current literature and identified 57 studies, performed in fourteen different countries, that investigated SNCA variants and susceptibility to PD. We discussed the findings based on environmental factors, history of PD, clinical outcomes, and ethnicity. In conclusion, SNPs within the SNCA gene can modify the susceptibility to PD, leading to increased or decreased risk. The risk associations of some SNPs varied among samples. Of notice, no studies in South American or African populations were found. There is little information about the effects of these variants on particular clinical aspects of PD, such as motor and nonmotor symptoms. Similarly, evidence of possible interactions between SNCA SNPs and environmental factors or disease progression is scarce. There is a need to expand the clinical applicability of these data as well as to investigate the role of SNCA SNPs in populations with different ethnic backgrounds.

The role of α-synuclein in neurodegeneration — An update

2012 ◽  
Vol 3 (2) ◽  
Author(s):  
Kurt Jellinger
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Bound States ◽  
Physiological Function ◽  
Neuronal Degeneration ◽  
Association Studies ◽  
Common Mechanism ◽  
Genome Wide Association Studies ◽  
Potential Biomarker

AbstractGenetic, neuropathological and biochemical evidence implicates α-synuclein, a 140 amino acid presynaptic neuronal protein, in the pathogenesis of Parkinson’s disease and other neurodegenerative disorders. The aggregated protein inclusions mainly containing aberrant α-synuclein are widely accepted as morphological hallmarks of α-synucleinopathies, but their composition and location vary between disorders along with neuronal networks affected. α-Synuclein exists physiologically in both soluble and membran-bound states, in unstructured and α-helical conformations, respectively, while posttranslational modifications due to proteostatic deficits are involved in β-pleated aggregation resulting in formation of typical inclusions. The physiological function of α-synuclein and its role linked to neurodegeneration, however, are incompletely understood. Soluble oligomeric, not fully fibrillar α-synuclein is thought to be neurotoxic, main targets might be the synapse, axons and glia. The effects of aberrant α-synuclein include alterations of calcium homeostasis, mitochondrial dysfunction, oxidative and nitric injuries, cytoskeletal effects, and neuroinflammation. Proteasomal dysfunction might be a common mechanism in the pathogenesis of neuronal degeneration in α-synucleinopathies. However, how α-synuclein induces neurodegeneration remains elusive as its physiological function. Genome wide association studies demonstrated the important role for genetic variants of the SNCA gene encoding α-synuclein in the etiology of Parkinson’s disease, possibly through effects on oxidation, mitochondria, autophagy, and lysosomal function. The neuropathology of synucleinopathies and the role of α-synuclein as a potential biomarker are briefly summarized. Although animal models provided new insights into the pathogenesis of Parkinson disease and multiple system atrophy, most of them do not adequately reproduce the cardinal features of these disorders. Emerging evidence, in addition to synergistic interactions of α-synuclein with various pathogenic proteins, suggests that prionlike induction and seeding of α-synuclein could lead to the spread of the pathology and disease progression. Intervention in the early aggregation pathway, aberrant cellular effects, or secretion of α-synuclein might be targets for neuroprotection and disease-modifying therapy.

scholarly journals Type 2 diabetes as a determinant of Parkinson’s disease risk and progression

2020 ◽  
Author(s):  
Harneek Chohan ◽  
Konstantin Senkevich ◽  
Radhika K Patel ◽  
Jonathan P Bestwick ◽  
Benjamin M Jacobs ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Observational Studies ◽  
Association Studies ◽  
Meta Analysis ◽  
Genome Wide Association Studies ◽  
Increased Risk ◽  
Summary Data

ABSTRACTObjectiveTo investigate type 2 diabetes mellitus (T2DM) as a determinant of Parkinson’s disease (PD) through a meta-analysis of observational and genetic summary data.MethodsA systematic review and meta-analysis of observational studies was undertaken by searching six databases. We selected the highest quality studies investigating the association of T2DM with PD risk and progression. We then used Mendelian randomization (MR) to investigate causal effects of genetic liability towards T2DM on PD risk and progression, using summary data derived from genome-wide association studies.ResultsIn the observational part of the study, nine studies were included in the risk meta-analysis and four studies were included in the progression meta-analysis. Pooled effect estimates revealed that T2DM was associated with an increased risk of PD (OR 1.21, 95% CI 1.07-1.36), and there was some evidence that T2DM was associated with faster progression of motor symptoms (SMD 0.55, 95% CI 0.39-0.72) and cognitive decline (SMD −0.92, 95% CI −1.50 – −0.34). Using MR we found supportive evidence for a causal effect of diabetes on PD risk (IVW OR 1.08, 95% CI 1.02-1.14; p=0.010) and some evidence of an effect on motor progression (IVW OR 1.10, 95% CI 1.01-1.20; p=0.032), but not for cognitive progression.ConclusionUsing meta-analysis of traditional observational studies and genetic data, we observed convincing evidence for an effect of T2DM on PD risk, and new evidence to support a role in PD progression. Treatment of diabetes may be an effective strategy to prevent or slow progression of PD.

scholarly journals A genetic and transcriptomic assessment of the KTN1 gene in Parkinson’s disease risk

2021 ◽  
Author(s):  
Anni Moore ◽  
Sara Bandres-Ciga ◽  
Cornelis Blauwendraat ◽  
Monica Diez-Fairen
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Disease Risk ◽  
Association Studies ◽  
Age At Onset ◽  
Brain Regions ◽  
Whole Genome Sequencing Data ◽  
Genome Wide Association Studies ◽  
Sequencing Data ◽  
Increased Risk

AbstractParkinson’s disease (PD) is a progressive neurological disorder caused by both genetic and environmental factors. A recent finding has suggested an association between KTN1 genetic variants and changes in its expression in the putamen and substantia nigra brain regions and an increased risk for PD. Here, we examine the link between PD susceptibility and KTN1 using individual-level genotyping data and summary statistics from the most recent genome-wide association studies (GWAS) for PD risk and age at onset from the International Parkinson’s Disease Genomics Consortium (IPDGC), as well as whole-genome sequencing data from the Accelerating Medicines Partnership Parkinson’s disease (AMP-PD) initiative. To investigate the potential effect of changes in KTN1 expression on PD compared to healthy individuals, we further assess publicly available expression quantitative trait loci (eQTL) results from GTEx v8 and BRAINEAC and transcriptomics data from AMP-PD. Overall, we found no genetic associations between KTN1 and PD in our cohorts but found potential evidence of differences in mRNA expression, which needs to be further explored.

scholarly journals Targeted sequencing of Parkinson’s disease loci genes highlights SYT11, FGF20 and other associations

Brain ◽  
2020 ◽  
Author(s):  
Uladzislau Rudakou ◽  
Eric Yu ◽  
Lynne Krohn ◽  
Jennifer A Ruskey ◽  
Farnaz Asayesh ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Linkage Disequilibrium ◽  
Rare Variants ◽  
Association Studies ◽  
Strong Linkage Disequilibrium ◽  
Genome Wide Association Studies ◽  
Common Variants ◽  
Common Genetic Variants

Abstract Genome-wide association studies (GWAS) have identified numerous loci associated with Parkinson’s disease. The specific genes and variants that drive the associations within the vast majority of these loci are unknown. We aimed to perform a comprehensive analysis of selected genes to determine the potential role of rare and common genetic variants within these loci. We fully sequenced 32 genes from 25 loci previously associated with Parkinson’s disease in 2657 patients and 3647 controls from three cohorts. Capture was done using molecular inversion probes targeting the exons, exon-intron boundaries and untranslated regions (UTRs) of the genes of interest, followed by sequencing. Quality control was performed to include only high-quality variants. We examined the role of rare variants (minor allele frequency < 0.01) using optimized sequence Kernel association tests. The association of common variants was estimated using regression models adjusted for age, sex and ethnicity as required in each cohort, followed by a meta-analysis. After Bonferroni correction, we identified a burden of rare variants in SYT11, FGF20 and GCH1 associated with Parkinson’s disease. Nominal associations were identified in 21 additional genes. Previous reports suggested that the SYT11 GWAS association is driven by variants in the nearby GBA gene. However, the association of SYT11 was mainly driven by a rare 3′ UTR variant (rs945006601) and was independent of GBA variants (P = 5.23 × 10−5 after exclusion of all GBA variant carriers). The association of FGF20 was driven by a rare 5′ UTR variant (rs1034608171) located in the promoter region. The previously reported association of GCH1 with Parkinson’s disease is driven by rare non-synonymous variants, some of which are known to cause dopamine-responsive dystonia. We also identified two LRRK2 variants, p.Arg793Met and p.Gln1353Lys, in 10 and eight controls, respectively, but not in patients. We identified common variants associated with Parkinson’s disease in MAPT, TMEM175, BST1, SNCA and GPNMB, which are all in strong linkage disequilibrium with known GWAS hits in their respective loci. A common coding PM20D1 variant, p.Ile149Val, was nominally associated with reduced risk of Parkinson’s disease (odds ratio 0.73, 95% confidence interval 0.60–0.89, P = 1.161 × 10−3). This variant is not in linkage disequilibrium with the top GWAS hits within this locus and may represent a novel association. These results further demonstrate the importance of fine mapping of GWAS loci, and suggest that SYT11, FGF20, and potentially PM20D1, BST1 and GPNMB should be considered for future studies as possible Parkinson’s disease-related genes.

scholarly journals SNCA 3′ UTR Genetic Variants in Patients with Parkinson’s Disease

Biomolecules ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1799
Author(s):  
Antonela Blažeković ◽  
Kristina Gotovac Jerčić ◽  
Fran Borovečki
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Genetic Variants ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
Nucleotide Polymorphisms ◽  
Snca Gene ◽  
Control Subjects ◽  
Genotype Frequencies ◽  
Healthy Control

The SNCA (Synuclein Alpha) gene represents a major risk gene for Parkinson’s disease (PD) and SNCA polymorphisms have been associated with the common sporadic form of PD. Numerous Genome-Wide Association Studies showed strong signals located in the SNCA 3′ UTR (untranslated region) region indicating that variants in 3′ UTRs of PD-associated genes could contribute to neurodegeneration and may regulate the risk for PD. Genetic variants in 3′ UTR can affect miRNA activity and consequently change the translation process. The aim of this study was to access the differences in 3′ UTR variants of SNCA genes in a cohort of PD patients and control subjects from Croatia. The cohort consisted of 52 PD patients and 23 healthy control subjects. Differences between 3′UTR allele and genotype frequencies were accessed through next generation sequencing approach from whole blood samples. In our study, we identified four previously reported single nucleotide polymorphisms (SNPs) and one insertion in the 3′ UTR region of SNCA gene, namely rs1045722, rs3857053, rs577490090, rs356165, and rs777296100, and five variants not reported in the literature, namely rs35270750, rs529553259, rs377356638, rs571454522, and rs750347645. Our results indicate a significantly higher occurrence of the rs571454522 variant in the PD population. To the best of our knowledge, this variant has not been reported until now in the literature. We analyzed our results in the context of previous research, creating a brief overview of the importance of 3′ UTR variants of the SNCA gene. Further studies will be needed to gain a more profound insight regarding their role in PD development, which will help to assess the role and impact of post-transcriptional regulation on disease pathology.

scholarly journals Targeted sequencing of Parkinson's disease loci genes highlights SYT11, FGF20 and other associations

2020 ◽  
Author(s):  
Uladzislau Rudakou ◽  
Eric Yu ◽  
Lynne M Krohn ◽  
Jennifer A Ruskey ◽  
Farnaz Asayesh ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Rare Variants ◽  
Association Studies ◽  
Meta Analysis ◽  
Strong Linkage Disequilibrium ◽  
Genome Wide Association Studies ◽  
Common Variants ◽  
Common Genetic Variants

Genome-wide association studies (GWAS) have identified numerous loci associated with Parkinson's disease. The specific genes and variants that drive the associations within the vast majority of these loci are unknown. We aimed to perform a comprehensive analysis of selected genes to determine the potential role of rare and common genetic variants within these loci. We fully sequenced 32 genes from 25 loci previously associated with Parkinson's disease in 2,657 patients and 3,647 controls from three cohorts. Capture was done using molecular inversion probes targeting the exons, exon-intron boundaries and untranslated regions (UTRs) of the genes of interest, followed by sequencing. Quality control was performed to include only high-quality variants. We examined the role of rare variants (minor allele frequency < 0.01) using optimized sequence Kernel association tests (SKAT-O). The association of common variants was estimated using regression models adjusted for age, sex and ethnicity as required in each cohort, followed by a meta-analysis. After Bonferroni correction, we identified a burden of rare variants in SYT11, FGF20 and GCH1 associated with Parkinson's disease. Nominal associations were identified in 21 additional genes. Previous reports suggested that the SYT11 GWAS association is driven by variants in the nearby GBA gene. However, the association of SYT11 was mainly driven by a rare 3' UTR variant (rs945006601) and was independent of GBA variants (p=5.23E-05 after exclusion of all GBA variant carriers). The association of FGF20 was driven by a rare 5' UTR variant (rs1034608171) located in the promoter region. The previously reported association of GCH1 with Parkinson's Disease is driven by rare nonsynonymous variants, some of which are known to cause dopamine-responsive dystonia. We also identified two LRRK2 variants, p.Arg793Met and p.Gln1353Lys, in ten and eight controls, respectively, but not in patients. We identified common variants associated with Parkinson's disease in MAPT, TMEM175, BST1, SNCA and GPNMB which are all in strong linkage disequilibrium (LD) with known GWAS hits in their respective loci. A common coding PM20D1 variant, p.Ile149Val, was nominally associated with reduced risk of Parkinson's disease (OR 0.73, 95% CI 0.60-0.89, p=1.161E-03). This variant is not in LD with the top GWAS hits within this locus and may represent a novel association. These results further demonstrate the importance of fine mapping of GWAS loci, and suggest that SYT11, FGF20, and potentially PM20D1, BST1 and GPNMB should be considered for future studies as possible Parkinson's disease-related genes.

scholarly journals Genome‐wide association studies of LRRK2 modifiers of Parkinson's disease

2021 ◽  
Author(s):  
Dongbing Lai ◽  
Babak Alipanahi ◽  
Pierre Fontanillas ◽  
Tae‐Hwi Schwantes‐An ◽  
Jan Aasly ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Association Studies ◽  
Genome Wide Association ◽  
Genome Wide Association Studies ◽  
Genome Wide

scholarly journals Causal Association between Periodontitis and Parkinson’s Disease: A Bidirectional Mendelian Randomization Study

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 772
Author(s):  
João Botelho ◽  
Vanessa Machado ◽  
José João Mendes ◽  
Paulo Mascarenhas
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Instrumental Variables ◽  
Mendelian Randomization ◽  
Association Studies ◽  
European Ancestry ◽  
Genome Wide Association Studies ◽  
Nucleotide Polymorphisms ◽  
Genetic Liability ◽  
Bidirectional Association

The latest evidence revealed a possible association between periodontitis and Parkinson’s disease (PD). We explored the causal relationship of this bidirectional association through two-sample Mendelian randomization (MR) in European ancestry populations. To this end, we used openly accessible data of genome-wide association studies (GWAS) on periodontitis and PD. As instrumental variables for periodontitis, seventeen single-nucleotide polymorphisms (SNPs) from a GWAS of periodontitis (1817 periodontitis cases vs. 2215 controls) and eight non-overlapping SNPs of periodontitis from an additional GWAS for validation purposes. Instrumental variables to explore for the reverse causation included forty-five SNPs from a GWAS of PD (20,184 cases and 397,324 controls). Multiple approaches of MR were carried-out. There was no evidence of genetic liability of periodontitis being associated with a higher risk of PD (B = −0.0003, Standard Error [SE] 0.0003, p = 0.26). The eight independent SNPs (B = −0.0000, SE 0.0001, p = 0.99) validated this outcome. We also found no association of genetically primed PD towards periodontitis (B = −0.0001, SE 0.0001, p = 0.19). These MR study findings do not support a bidirectional causal genetic liability between periodontitis and PD. Further GWAS studies are needed to confirm the consistency of these results.

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