Mild cognitive impairment among LRRK2 and GBA1 patients with Parkinson's disease.

BACKGROUND: Mild cognitive impairment (MCI) is common in Parkinson's disease (PD). We aimed to assess the incidence of MCI among patients with PD, carriers of mutations in LRRK2 and GBA1 genes, based on the movement disorder society (MDS) criteria for the diagnosis of MCI in early-stage PD. METHODS: Patients with PD were included if they scored ≤2 on the Hoehn and Yahr and ≤6 years since motor symptom onset. A group of age and gender matched healthy adults served as controls. A neuropsychological cognitive battery was used covering five cognitive domains (executive functions, working memory, memory, visuospatial and language). MCI was explored while applying two methods (level I and II). Frequency of MCI was assessed in comparison between groups. RESULTS: 70 patients with idiopathic PD (iPD) (68 % males), 42 patients with LRRK2-PD (61 % males), 83 patients with GBA1-PD (63 % males) and 132 age and gender matched controls (61 % males), participated in this study. PD groups were similar in clinical characteristics. Level I criteria were positive in 57.5 % of iPD, 43 % of LRRK2-PD and 63.4 % of the GBA1-PD (p = 0.071). Level II criteria was met by 39 % of iPD, 14 % LRRK2-PD and 41 % of GBA1-PD (p < 0.001), when using a 2 standard-deviation (SD) threshold. GBA1-PD and iPD showed impairments on multiple domains even in the more conservative 2 SD, reflecting MCI. CONCLUSIONS: The majority of our PD cohort was classified as MCI when assessed with strict criteria. GBA1-PD and iPD showed a more widespread pattern of MCI compared with LRRK2-PD.

The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons.

Background: Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified. Methods: Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils. Results: We first identified specific non-coding variants in CTSB that drive the association with PD and are linked to changes in brain CTSB expression levels. Using iPSC-derived dopaminergic neurons we then find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1) activity, and leads to an accumulation of lysosomal content. Moreover, in cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. Similarly, in midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition or knockout potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein. Conclusions: The results of our genetic and functional studies indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

GBA1-and LRRK2-directed Treatments: The Way Forward.

There is an urgent need to identify drug targets for disease modification in Parkinson's Disease (PD). In this mini-review we highlight the reasons genetically-defined drug targets show great promise. Specifically, clinical trials targeting the glucocerebrosidase-1 (GBA1) and leucine-rich repeat kinase 2 (LRRK2) genes are underway. Two key knowledge gaps are 1. How should we modify the GBA1 and LRRK2 pathways? and 2. Which patient populations are most likely to benefit? The exact mechanisms by which mutations in these genes cause PD are not fully understood. Most drugs targeting the GBA1 pathway in clinical trials aim at increasing glucocerebrosidase enzymatic (GCase) activity and targeting the LRRK2 pathway, at reducing its kinase activity. Carriers of mutations in these genes are natural candidates for such interventions; however, there are some biomarker data, specifically for GBA1, to support studying such interventions in non-carriers, i.e., sporadic PD. In summary, we anticipate significant progress in our path towards precision medicine in PD in the coming years.

PINK1 is a target of T cell responses in Parkinson's disease.

Parkinson's disease (PD) is associated with autoimmune T cells that recognize the protein alpha-synuclein in a subset of individuals. Multiple neuroantigens are targets of autoinflammatory T cells in classical central nervous system autoimmune diseases such as multiple sclerosis (MS). Here, we explored whether additional autoantigenic targets of T cells in PD. We generated 15-mer peptide pools spanning several PD-related proteins implicated in PD pathology, including GBA, SOD1, PINK1, parkin, OGDH, and LRRK2. Cytokine production (IFNγ, IL-5, IL-10) against these proteins was measured using a fluorospot assay and PBMCs from patients with PD and age-matched healthy controls. This approach identified unique epitopes and their HLA restriction from the mitochondrial-associated protein PINK1, a regulator of mitochondrial stability, as an autoantigen targeted by T cells. The T cell reactivity was predominantly found in male patients with PD, which may contribute to the heterogeneity of PD. Identifying and characterizing PINK1 and other autoinflammatory targets may lead to antigen-specific diagnostics, progression markers, and/or novel therapeutic strategies for PD.

Distinctive CD56dim NK subset profiles and increased NKG2D expression in blood NK cells of Parkinson's disease patients.

Mounting data suggest an important role for the immune system in Parkinson's disease (PD). Previous evidence of increased natural killer (NK) cell populations in PD suggests a potential role of NK cells in the pathogenesis of the disease. Previous studies have analyzed NK cell populations using aggregation by variable expression of CD56 and CD16. It remains unknown what differences may exist between NK cell subpopulations when stratified using more nuanced classification. Here, we profile NK cell subpopulations and elucidate the expressions of activating, NKG2D, inhibitory, NKG2A, and homing, CX3CR1, receptors on NK cell subpopulations in PD and healthy controls (HC). We analyzed cryopreserved PMBC samples using a 10-color flow cytometry panel to evaluate NK cell subpopulations in 31 individuals with sporadic PD and 27 HC participants. Here we identified significant differences in the CD56dim NK subset that changes with disease severity in PD. Furthermore, the expressions of NKG2D in all three NK cell subsets were significantly elevated in PD patients compared to HC. Notably, NKG2A expression in the CD56bright NK subset increased in PD patients with longer disease duration but there were no changes in CX3CR1. In summary, our data suggests that changes in NK cells may be influenced by the clinical severity and duration of PD.

A potential patient stratification biomarker for Parkinson´s disease based on LRRK2 kinase-mediated centrosomal alterations in peripheral blood-derived cells.

Parkinson´s disease (PD) is a common neurodegenerative movement disorder and leucine-rich repeat kinase 2 (LRRK2) is a promising therapeutic target for disease intervention. However, the ability to stratify patients who will benefit from such treatment modalities based on shared etiology is critical for the success of disease-modifying therapies. Ciliary and centrosomal alterations are commonly associated with pathogenic LRRK2 kinase activity and can be detected in many cell types. We previously found centrosomal deficits in immortalized lymphocytes from G2019S-LRRK2 PD patients. Here, to investigate whether such deficits may serve as a potential blood biomarker for PD which is susceptible to LRKK2 inhibitor treatment, we characterized patient-derived cells from distinct PD cohorts. We report centrosomal alterations in peripheral cells from a subset of early-stage idiopathic PD patients which is mitigated by LRRK2 kinase inhibition, supporting a role for aberrant LRRK2 activity in idiopathic PD. Centrosomal defects are detected in R1441G-LRRK2 and G2019S-LRRK2 PD patients and in non-manifesting LRRK2 mutation carriers, indicating that they accumulate prior to a clinical PD diagnosis. They are present in immortalized cells as well as in primary lymphocytes from peripheral blood. These findings indicate that analysis of centrosomal defects as a blood-based patient stratification biomarker may help nominate idiopathic PD patients who will benefit from LRRK2-related therapeutics.

The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons.

Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified. Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils. We find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1) activity, and leads to an accumulation of lysosomal content. In cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. In midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein. These results indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

Establishing an online resource to facilitate global collaboration and inclusion of underrepresented populations: Experience from the MJFF Global Genetic Parkinson's Disease Project.

Parkinson's disease (PD) is the fastest-growing neurodegenerative disorder, currently affecting ~7 million people worldwide. PD is clinically and genetically heterogeneous, with at least 10% of all cases explained by a monogenic cause or strong genetic risk factor. However, the vast majority of our present data on monogenic PD is based on the investigation of patients of European White ancestry, leaving a large knowledge gap on monogenic PD in underrepresented populations. Gene-targeted therapies are being developed at a fast pace and have started entering clinical trials. In light of these developments, building a global network of centers working on monogenic PD, fostering collaborative research, and establishing a clinical trial-ready cohort is imperative. Based on a systematic review of the English literature on monogenic PD and a successful team science approach, we have built up a network of 59 sites worldwide and have collected information on the availability of data, biomaterials, and facilities. To enable access to this resource and to foster collaboration across centers, as well as between academia and industry, we have developed an interactive map and online tool allowing for a quick overview of available resources, along with an option to filter for specific items of interest. This initiative is currently being merged with the Global Parkinson's Genetics Program (GP2), which will attract additional centers with a focus on underrepresented sites. This growing resource and tool will facilitate collaborative research and impact the development and testing of new therapies for monogenic and potentially for idiopathic PD patients.

Myasthenia gravis patients exhibiting an eyelid myotonia-like phenomenon.

We report here a retrospective case series of 3 MG patients suffering from difficulty opening eyes that appeared together with a diagnosis of MG. All are male patients with late-onset MG who are seropositive for anti-acetylcholine receptor antibodies. The phenomenon was characterized by difficulty opening the eyes after forced closure or reflex eye closure, improving with the ice pack test and with repeated forced eye closure but worsening with pyridostigmine treatment. We provide a detailed clinical, serological, imaging and electrophysiological examination of these patients. Electromyography evaluation did not show spontaneous muscle activity or myotonia at rest in the orbital part of the orbicularis oculi muscle. However, there was sustained muscle activity lasting several seconds in the pre-tarsal and pre-septal parts of this muscle. Videos of those reported symptoms were produced and provided. We discuss the possible neurological pathophysiology of this disorder and suggest to name this rare ocular disorder "myotonia-like disorder of the pre-tarsal and pre-septal parts of the orbicularis oculi". This study expands our knowledge of this rare clinical feature of MG and highlights the need for increased awareness of it and further investigation of this ocular manifestation.

A blood-based marker of mitochondrial DNA damage in Parkinson's disease.

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, and neuroprotective or disease-modifying interventions remain elusive. High-throughput markers aimed at stratifying patients on the basis of shared etiology are required to ensure the success of disease-modifying therapies in clinical trials. Mitochondrial dysfunction plays a prominent role in the pathogenesis of PD. Previously, we found brain region-specific accumulation of mitochondrial DNA (mtDNA) damage in PD neuronal culture and animal models, as well as in human PD postmortem brain tissue. To investigate mtDNA damage as a potential blood-based marker for PD, we describe herein a PCR-based assay (Mito DNADX) that allows for the accurate real-time quantification of mtDNA damage in a scalable platform. We found that mtDNA damage was increased in peripheral blood mononuclear cells derived from patients with idiopathic PD and those harboring the PD-associated leucine-rich repeat kinase 2 (LRRK2) G2019S mutation in comparison with age-matched controls. In addition, mtDNA damage was elevated in non-disease-manifesting LRRK2 mutation carriers, demonstrating that mtDNA damage can occur irrespective of a PD diagnosis. We further established that Lrrk2 G2019S knock-in mice displayed increased mtDNA damage, whereas Lrrk2 knockout mice showed fewer mtDNA lesions in the ventral midbrain, compared with wild-type control mice. Furthermore, a small-molecule kinase inhibitor of LRRK2 mitigated mtDNA damage in a rotenone PD rat midbrain neuron model and in idiopathic PD patient-derived lymphoblastoid cell lines. Quantifying mtDNA damage using the Mito DNADX assay may have utility as a candidate marker of PD and for measuring the pharmacodynamic response to LRRK2 kinase inhibitors.

Safety and efficacy of venglustat in GBA1-associated Parkinson's disease: an international, multicentre, double-blind, randomised, placebo-controlled, phase 2 trial.

BACKGROUND: Variants in the GBA1 gene, which encodes lysosomal acid glucocerebrosidase, are among the most common genetic risk factors for Parkinson's disease and are associated with faster disease progression. The mechanisms involved are unresolved but might include accumulation of glucosylceramide. Venglustat is a brain-penetrant glucosylceramide synthase inhibitor that, in previous studies, reduced amounts of the glycosphingolipid. We aimed to assess the safety, efficacy, and target engagement of venglustat in people with early-stage Parkinson's disease carrying pathogenic GBA1 variants. METHODS: MOVES-PD part 2 was a randomised, double-blinded, placebo-controlled phase 2 study done at 52 centres (academic sites, specialty clinics, and general neurology centres) in 16 countries. Eligible adults aged 18-80 years with Parkinson's disease (Hoehn and Yahr stage ≤2) and one or more GBA1 variants were randomly assigned using an interactive voice-response system (1:1) to 52 weeks of treatment with oral venglustat (15 mg/day) or matching placebo. Investigators, site personnel, participants, and their caregivers were masked to treatment allocation. The primary outcome measure was the change from baseline to 52 weeks in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) parts II and III combined score (a higher score indicates greater impairment), and it was analysed in a modified intention-to-treat population (ie, all randomly assigned participants with a baseline and at least one post-baseline measurement during the treatment period). This study was registered with ClinicalTrials.gov (NCT02906020) and is closed to recruitment. FINDINGS: Between Dec 15, 2016, and May 27, 2021, 221 participants were randomly assigned to venglustat (n=110) or placebo (n=111). The least squares mean change in MDS-UPDRS parts II and III combined score was 7·29 (SE 1·36) for venglustat (n=96) and 4·71 (SE 1·27) for placebo (n=105); the absolute difference between groups was 2·58 (95% CI -1·10 to 6·27; p=0·17). The most common treatment-emergent adverse events (TEAEs) were constipation and nausea (both were reported by 23 [21%] of 110 participants in the venglustat group and eight [7%] of 111 participants in the placebo group). Serious TEAEs were reported for 12 (11%) participants in each group. There was one death in the venglustat group owing to an unrelated cardiopulmonary arrest and there were no deaths in the placebo group. INTERPRETATION: In people with GBA1-associated Parkinson's disease in our study, venglustat had a satisfactory safety profile but showed no beneficial treatment effect compared with placebo. These findings indicate that glucosylceramide synthase inhibition with venglustat might not be a viable therapeutic approach for GBA1-associated Parkinson's disease. FUNDING: Sanofi.

International Genetic Testing and Counseling Practices for Parkinson's Disease.

BACKGROUND: There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing. OBJECTIVES: The aim is to determine the international landscape of genetic testing in PD to inform future worldwide recommendations. METHODS: A web-based survey assessing current practices, concerns, and barriers to genetic testing and counseling was administered to the International Parkinson and Movement Disorders Society membership. RESULTS: Common hurdles across sites included cost and access to genetic testing, and counseling, as well as education on genetic counseling. Region-dependent differences in access to and availability of testing and counseling were most notable in Africa. High-income countries also demonstrated heterogeneity, with European nations more likely to have genetic testing covered through insurance than Pan-American and Asian countries. CONCLUSIONS: This survey highlights not only diversity of barriers in different regions but also the shared and highly actionable needs for improved education and access to genetic counseling and testing for PD worldwide. © 2023 International Parkinson and Movement Disorder Society.

Providing genetic testing and genetic counseling for Parkinson's disease to the community.

PURPOSE: To evaluate the feasibility and impact of offering genetic testing and counseling to patients with Parkinson's disease (PD), with the potential to enroll in gene-targeted clinical trials and improve clinical care. METHODS: A multicenter, exploratory pilot study at 7 academic hospital sites in the United States tracked enrollment and randomized participants to receive results and genetic counseling at local sites or by genetic counselors, remotely. Follow-up surveys measured participant/provider satisfaction, knowledge, and psychological impact. RESULTS: From September 5, 2019 to January 4, 2021, 620 participants were enrolled and 387 completed outcome surveys. There were no significant differences in outcomes between local and remote sites, with both arms reporting high knowledge and satisfaction scores (>80%). Notably, 16% of those tested had reportable PD gene variants (pathogenic/likely pathogenic/risk allele). CONCLUSION: Local clinicians, as well as genetic counselors, with educational support as needed, can effectively return genetic results for PD as we observed favorable outcome measures in both groups. Increasing access to PD genetic testing and counseling is urgent; this can inform future efforts to integrate genetic testing and counseling into clinical care for all those with PD.

Genetic Testing in Parkinson's Disease.

Genetic testing for persons with Parkinson's disease is becoming increasingly common. Significant gains have been made regarding genetic testing methods, and testing is becoming more readily available in clinical, research, and direct-to-consumer settings. Although the potential utility of clinical testing is expanding, there are currently no proven gene-targeted therapies, but clinical trials are underway. Furthermore, genetic testing practices vary widely, as do knowledge and attitudes of relevant stakeholders. The specter of testing mandates financial, ethical, and physician engagement, and there is a need for guidelines to help navigate the myriad of challenges. However, to develop guidelines, gaps and controversies need to be clearly identified and analyzed. To this end, we first reviewed recent literature and subsequently identified gaps and controversies, some of which were partially addressed in the literature, but many of which are not well delineated or researched. Key gaps and controversies include: (1) Is genetic testing appropriate in symptomatic and asymptomatic individuals without medical actionability? (2) How, if at all, should testing vary based on ethnicity? (3) What are the long-term outcomes of consumer- and research-based genetic testing in presymptomatic PD? (4) What resources are needed for clinical genetic testing, and how is this impacted by models of care and cost-benefit considerations? Addressing these issues will help facilitate the development of consensus and guidelines regarding the approach and access to genetic testing and counseling. This is also needed to guide a multidisciplinary approach that accounts for cultural, geographic, and socioeconomic factors in developing testing guidelines. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Association of Rare Variants in ARSA with Parkinson's Disease.

BACKGROUND: Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA remains unclear. OBJECTIVES: To study rare ARSA variants in PD. METHODS: To study rare ARSA variants (minor allele frequency < 0.01) in PD, we performed burden analyses in six independent cohorts with 5801 PD patients and 20,475 controls, followed by a meta-analysis. RESULTS: We found evidence for associations between functional ARSA variants and PD in four cohorts (P ≤ 0.05 in each) and in the meta-analysis (P = 0.042). We also found an association between loss-of-function variants and PD in the United Kingdom Biobank cohort (P = 0.005) and in the meta-analysis (P = 0.049). These results should be interpreted with caution as no association survived multiple comparisons correction. Additionally, we describe two families with potential co-segregation of ARSA p.E382K and PD. CONCLUSIONS: Rare functional and loss-of-function ARSA variants may be associated with PD. Further replications in large case-control/familial cohorts are required. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Defining the Riddle in Order to Solve It: There Is More Than One "Parkinson's Disease".

BACKGROUND: More than 200 years after James Parkinsondescribed a clinical syndrome based on his astute observations, Parkinson's disease (PD) has evolved into a complex entity, akin to the heterogeneity of other complex human syndromes of the central nervous system such as dementia, motor neuron disease, multiple sclerosis, and epilepsy. Clinicians, pathologists, and basic science researchers evolved arrange of concepts andcriteria for the clinical, genetic, mechanistic, and neuropathological characterization of what, in their best judgment, constitutes PD. However, these specialists have generated and used criteria that are not necessarily aligned between their different operational definitions, which may hinder progress in solving the riddle of the distinct forms of PD and ultimately how to treat them. OBJECTIVE: This task force has identified current in consistencies between the definitions of PD and its diverse variants in different domains: clinical criteria, neuropathological classification, genetic subtyping, biomarker signatures, and mechanisms of disease. This initial effort for "defining the riddle" will lay the foundation for future attempts to better define the range of PD and its variants, as has been done and implemented for other heterogeneous neurological syndromes, such as stroke and peripheral neuropathy. We strongly advocate for a more systematic and evidence-based integration of our diverse disciplines by looking at well-defined variants of the syndrome of PD. CONCLUSION: Accuracy in defining endophenotypes of "typical PD" across these different but interrelated disciplines will enable better definition of variants and their stratification in therapeutic trials, a prerequisite for breakthroughs in the era of precision medicine. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Quantitative proteomics and phosphoproteomics of urinary extracellular vesicles define putative diagnostic biosignatures for Parkinson's disease.

BACKGROUND: Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene have been recognized as genetic risk factors for Parkinson's disease (PD). However, compared to cancer, fewer genetic mutations contribute to the cause of PD, propelling the search for protein biomarkers for early detection of the disease. METHODS: Utilizing 138 urine samples from four groups, healthy individuals (control), healthy individuals with G2019S mutation in the LRRK2 gene (non-manifesting carrier/NMC), PD individuals without G2019S mutation (idiopathic PD/iPD), and PD individuals with G2019S mutation (LRRK2 PD), we applied a proteomics strategy to determine potential diagnostic biomarkers for PD from urinary extracellular vesicles (EVs). RESULTS: After efficient isolation of urinary EVs through chemical affinity followed by mass spectrometric analyses of EV peptides and enriched phosphopeptides, we identify and quantify 4476 unique proteins and 2680 unique phosphoproteins. We detect multiple proteins and phosphoproteins elevated in PD EVs that are known to be involved in important PD pathways, in particular the autophagy pathway, as well as neuronal cell death, neuroinflammation, and formation of amyloid fibrils. We establish a panel of proteins and phosphoproteins as novel candidates for disease biomarkers and substantiate the biomarkers using machine learning, ROC, clinical correlation, and in-depth network analysis. Several putative disease biomarkers are further partially validated in patients with PD using parallel reaction monitoring (PRM) and immunoassay for targeted quantitation. CONCLUSIONS: These findings demonstrate a general strategy of utilizing biofluid EV proteome/phosphoproteome as an outstanding and non-invasive source for a wide range of disease exploration.

Parkinson's disease (PD) is a progressive neurological disorder that affects body movement because some brain cells stop producing the chemical dopamine. PD is often not diagnosed until it has advanced, making early detection crucial. To enable early detection, we investigated tiny packages called extracellular vesicles released from a variety of cells, including the brain cells, that can be found in urine as a potential source for diagnosing PD. These tiny packages contain different kinds of molecules from inside the cells. We analyzed urine samples from 138 individuals and found several proteins involved in PD development that could be biological indicators for early detection of the disease. We used various techniques to make sure that our findings were accurate. Our study suggests that looking at these proteins in urine could be a good way to detect PD in a non-invasive manner.

Novel variants in genes related to vesicle-mediated-transport modify Parkinson's disease risk.

OBJECTIVES: VPS35 and VPS13 have been associated with Parkinson's disease (PD), and their shared phenotype in yeast when reduced in function is abnormal vacuolar transport. We aim to test if additional potentially deleterious variants in other genes that share this phenotype can modify the risk for PD. METHODS: 77 VPS and VPS-related genes were analyzed using whole-genome-sequencing data from 202 PD patients of Ashkenazi Jewish (AJ) ancestry. Filtering was done based on quality and functionality scores. Ten variants in nine genes were further genotyped in 1200 consecutively recruited unrelated AJ-PD patients, and allele frequencies and odds ratio calculated compared to gnomAD-AJ-non-neuro database, in un-stratified (n = 1200) and stratified manner (LRRK2-G2019S-PD patients (n = 145), GBA-PD patients (n = 235), and non-carriers of these mutations (NC, n = 787)). RESULTS: Five variants in PIK3C3, VPS11, AP1G2, HGS and VPS13D were significantly associated with PD-risk. PIK3C3-R768W showed a significant association in an un-stratified (all PDs) analysis, as well as in stratified (LRRK2, GBA, and NC) analyses (Odds ratios = 2.71, 5.32, 3.26. and 2.19 with p = 0.0015, 0.002, 0.0287, and 0.0447, respectively). AP1G2-R563W was significantly associated in LRRK2-carriers (OR = 3.69, p = 0.006) while VPS13D-D2932N was significantly associated in GBA-carriers (OR = 5.45, p = 0.0027). VPS11-C846G and HGS-S243Y were significantly associated in NC (OR = 2.48 and 2.06, with p = 0.022 and 0.0163, respectively). CONCLUSIONS: Variants in genes involved in vesicle-mediated protein transport and recycling pathways, including autophagy and mitophagy, may differentially modify PD-risk in LRRK2-carriers, GBA carriers, or NC. Specifically, PIK3C3-R768W is a PD-risk allele, with the highest effect size in LRRK2-G2019S carriers. These results suggest oligogenic effect that may depends on the genetic background of the patient. An unbiased burden of mutations approach in these genes should be evaluated in additional PD and control groups. The mechanisms by which these novel variants interact and increase PD-risk should be researched in depth for better tailoring therapeutic intervention for PD prevention or slowing disease progression.

Enough vs. More: Neuropsychological testing is more useful than genetic testing in the baseline evaluation of Parkinson disease.

In conclusion, baseline neuropsychological testing provides a vast amount of unique cognitive, psychiatric, behavioral, and psychosocial information that is useful to individuals with PD, care partners, and treatment team providers. As a baseline examination, it provides opportunities for comparison purposes in the future, a prediction of risk assessment and future treatment needs, and at the time of evaluation for clinical treatment to improve quality of life. Such information is not captured by genetic testing, although the ideal path moving forward would be to perform both neuropsychological testing and genetic testing at baseline.