Heterozygous gain-of-kinase function variants in
LRRK2
(leucine-rich repeat kinase 2) cause 1–2% of all cases of Parkinson’s disease (PD) albeit with incomplete and age-dependent penetrance. All ...pathogenic LRRK2 mutations reside within the two catalytic domains of LRRK2—either in its kinase domain (e.g. G2019S) with modest effect or its ROC-COR GTPase domain (e.g. R1441G/H) with large effect on LRRK2 kinase activity. We have previously reported assays to interrogate LRRK2 kinase pathway activity in human bio-samples measuring phosphorylation of its endogenous substrate Rab10, that mirrors LRRK2 kinase activation status. Here, we isolated neutrophils from fresh peripheral blood from 101 participants including 42 LRRK2 mutation carriers (21 with the G2019S and 21 with the R1441G mutations), 27 patients with idiopathic PD, and 32 controls. Using a dual approach, LRRK2 dependent Rab10 phosphorylation at Threonine 73 (pRab10
Thr73
) was measured by quantitative multiplexed immunoblotting for pRab10
Thr73
/total Rab10 as well as targeted mass-spectrometry for absolute pRab10
Thr73
occupancy. We found a significant over fourfold increase in pRab10
Thr73
phosphorylation in carriers of the LRRK2 R1441G mutation irrespective of clinical disease status. The effect of the LRRK2 G2019S mutation did not reach statistical significance. Furthermore, we show that LRRK2 phosphorylation at Serine 935 is not a marker for LRRK2 kinase activity in human neutrophils. When analysing pRab10
Thr73
phosphorylation in post-mortem brain samples, we observed overall high variability irrespective of clinical and LRRK2 mutation status and attributed this mainly to the adverse effect of the peri- and post-mortem period on the stability of posttranslational modifications such as protein phosphorylation. Overall, in vivo LRRK2 dependent pRab10
Thr73
phosphorylation in human peripheral blood neutrophils is a specific, robust and promising biomarker for significant LRRK2 kinase hyperactivation, as with the LRRK2 R1441G mutation. Additional readouts and/or assays may be needed to increase sensitivity to detect modest LRRK2 kinase activation, as with the LRRK2 G2019S mutation. Our assays could be useful for patient stratification and target engagement studies for LRRK2 kinase inhibitors.
Background
The Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS‐UPDRS) is a newly developed tool to assess Parkinson's disease (PD). Changes in scores on the scale over the ...course of PD, including increasing disease duration and Hoehn and Yahr (HY) stages, have not been described. The objectives of this study were to analyze MDS‐UPDRS scores on Parts I through IV and their differences based on HY stage and disease duration in a large cohort of patients with PD.
Methods
For this cross‐sectional study, demographic data and MDS‐UPDRS scores were collected, including HY stage. Subscores on MDS‐UPDRS Parts I through IV were analyzed using 1‐way analyses of variance for each HY stage and in 5‐year increments of disease duration. Part III (motor assessment) scores were analyzed separately for on and off states.
Results
The mean age of the 3206 patients was 65.8 ± 10.6 years, 53.3% were men, the mean disease duration was 11.5 ± 4.6 years, and the median HY stage was 2 (range, 0–5); 2156 patients were examined in an on state and 987 were examined in an off state. Scores for all MDS‐UPDRS parts increased significantly through HY stages 1 through 5, with an average increase of 3.8, 7.7, 14.6, and 2.0 points consecutively for parts I through IV, respectively. For the 5‐year increments of disease duration, MDS‐UPDRS subscores increased by an average of 1.6, 3.3, 4.2, and 1.4 points consecutively for parts I through IV, respectively. This increase was significant only during the first 15 years of disease for all 4 parts, including part III scores evaluated in both on and off states.
Conclusions
MDS‐UPDRS scores for all 4 parts increase significantly with every HY stage and also with 5‐year increments of disease duration in the first 15 years of the disease.
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 Movement Disorder Society-UPDRS (MDS-UPDRS) was published in 2008, showing satisfactory clinimetric results and has been proposed as the official benchmark scale for Parkinson’s disease. The ...present study, based on the official MDS-UPDRS Spanish version, performed the first independent testing of the scale and adds information on its clinimetric properties. The cross-culturally adapted MDS-UPDRS Spanish version showed a comparative fit index ≥0.90 for each part (I–IV) relative to the English-language version and was accepted as the Official MDS-UPDRS Spanish version. Data from this scale, applied with other assessments to Spanish-speaking Parkinson’s disease patients in five countries, were analyzed for an independent and complementary clinimetric evaluation. In total, 435 patients were included. Missing data were negligible and moderate floor effect (30 %) was found for Part IV. Cronbach’s α index ranged between 0.79 and 0.93 and only five items did not reach the 0.30 threshold value of item-total correlation. Test–retest reliability was adequate with only two sub-scores of the item 3.17, Rest tremor amplitude, reaching κ values lower than 0.60. The intraclass correlation coefficient was higher than 0.85 for the total score of each part. Correlation of the MDS-UPDRS parts with other measures for related constructs was high (≥0.60) and the standard error of measurement lower than one-third baseline standard deviation for all subscales. Results confirm those of the original study and add information on scale reliability, construct validity, and precision. The MDS-UPDRS Spanish version shows satisfactory clinimetric characteristics.
Parkinson's disease is a neurodegenerative movement disorder that currently has no disease-modifying treatment, partly owing to inefficiencies in drug target identification and validation. We use ...Mendelian randomization to investigate over 3,000 genes that encode druggable proteins and predict their efficacy as drug targets for Parkinson's disease. We use expression and protein quantitative trait loci to mimic exposure to medications, and we examine the causal effect on Parkinson's disease risk (in two large cohorts), age at onset and progression. We propose 23 drug-targeting mechanisms for Parkinson's disease, including four possible drug repurposing opportunities and two drugs which may increase Parkinson's disease risk. Of these, we put forward six drug targets with the strongest Mendelian randomization evidence. There is remarkably little overlap between our drug targets to reduce Parkinson's disease risk versus progression, suggesting different molecular mechanisms. Drugs with genetic support are considerably more likely to succeed in clinical trials, and we provide compelling genetic evidence and an analysis pipeline to prioritise Parkinson's disease drug development.
Abstract Objective To evaluate the motor experiences of daily living section of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS M-EDL) for assessing disability in ...PD patients; to determine the association between disability and quality of life; and to identify cut-off score ranges for no, mild, moderate and severe disability with this measure. Methods International, observational, cross-sectional study of 435 PD patients, assessed with: MDS-UPDRS, Hoehn and Yahr staging, Rapid Assessment of Disability Scale, Clinical Impression of Severity Index for PD, Parkinson's Disease Questionnaire-8 and EQ-5D. Descriptive statistics, Spearman's rank correlation coefficients, Kruskal–Wallis test for group comparisons, ordinal logistic regression analysis for setting cut-off values and a step-wise multiple linear regression model were calculated. Results MDS-UPDRS M-EDL correlated 0.70–0.80 with other disability measures, and −0.46 to 0.74 with quality of life scales. Scores significantly increased with higher disease duration and severity ( p < 0.001). Cut-off values for the M-EDL were: 0–2 points, no disability; 3–16, mild; 17–31, moderate; and 32 points or more, severe. Linear regression analysis identified the MDS-UPDRS nM-EDL section as the main determinant of M-EDL, followed by the rest of MDS-UPDRS sections (explained variance: 59%). Conclusions MDS-UPDRS M-EDL proved to be useful for assessing disability in PD.
Dystonia is a neurological disorder characterized by sustained or intermittent muscle contractions causing abnormal movements and postures, often occurring in absence of any structural brain ...abnormality. Psychiatric comorbidities, including anxiety, depression, obsessive-compulsive disorder and schizophrenia, are frequent in patients with dystonia. While mutations in a fast-growing number of genes have been linked to Mendelian forms of dystonia, the cellular, anatomical, and molecular basis remains unknown for most genetic forms of dystonia, as does its genetic and biological relationship to neuropsychiatric disorders. Here we applied an unbiased systems-biology approach to explore the cellular specificity of all currently known dystonia-associated genes, predict their functional relationships, and test whether dystonia and neuropsychiatric disorders share a genetic relationship. To determine the cellular specificity of dystonia-associated genes in the brain, single-nuclear transcriptomic data derived from mouse brain was used together with expression-weighted cell-type enrichment. To identify functional relationships among dystonia-associated genes, we determined the enrichment of these genes in co-expression networks constructed from 10 human brain regions. Stratified linkage-disequilibrium score regression was used to test whether co-expression modules enriched for dystonia-associated genes significantly contribute to the heritability of anxiety, major depressive disorder, obsessive-compulsive disorder, schizophrenia, and Parkinson's disease. Dystonia-associated genes were significantly enriched in adult nigral dopaminergic neurons and striatal medium spiny neurons. Furthermore, 4 of 220 gene co-expression modules tested were significantly enriched for the dystonia-associated genes. The identified modules were derived from the substantia nigra, putamen, frontal cortex, and white matter, and were all significantly enriched for genes associated with synaptic function. Finally, we demonstrate significant enrichments of the heritability of major depressive disorder, obsessive-compulsive disorder and schizophrenia within the putamen and white matter modules, and a significant enrichment of the heritability of Parkinson's disease within the substantia nigra module. In conclusion, multiple dystonia-associated genes interact and contribute to pathogenesis likely through dysregulation of synaptic signalling in striatal medium spiny neurons, adult nigral dopaminergic neurons and frontal cortical neurons. Furthermore, the enrichment of the heritability of psychiatric disorders in the co-expression modules enriched for dystonia-associated genes indicates that psychiatric symptoms associated with dystonia are likely to be intrinsic to its pathophysiology.
Objective
Parkinson's disease (PD) is a complex neurodegenerative disorder. Men are on average ~ 1.5 times more likely to develop PD compared to women with European ancestry. Over the years, ...genomewide association studies (GWAS) have identified numerous genetic risk factors for PD, however, it is unclear whether genetics contribute to disease etiology in a sex‐specific manner.
Methods
In an effort to study sex‐specific genetic factors associated with PD, we explored 2 large genetic datasets from the International Parkinson's Disease Genomics Consortium and the UK Biobank consisting of 13,020 male PD cases, 7,936 paternal proxy cases, 89,660 male controls, 7,947 female PD cases, 5,473 maternal proxy cases, and 90,662 female controls. We performed GWAS meta‐analyses to identify distinct patterns of genetic risk contributing to disease in male versus female PD cases.
Results
In total, 19 genomewide significant regions were identified and no sex‐specific effects were observed. A high genetic correlation between the male and female PD GWAS were identified (rg = 0.877) and heritability estimates were identical between male and female PD cases (~ 20%).
Interpretation
We did not detect any significant genetic differences between male or female PD cases. Our study does not support the notion that common genetic variation on the autosomes could explain the difference in prevalence of PD between males and females cases at least when considering the current sample size under study. Further studies are warranted to investigate the genetic architecture of PD explained by X and Y chromosomes and further evaluate environmental effects that could potentially contribute to PD etiology in male versus female patients. ANN NEUROL 2021;90:41–48
PDF
