Genetic meta-analysis of levodopa induced dyskinesia in Parkinson's disease

Importance

Forty percent of Parkinson's disease patients develop levodopa-induced-dyskinesia (LiD) within 4 years of starting levodopa. The genetic basis of LiD remains poorly understood, and there have been few well powered studies.

Objective

To discover common genetic variants in the PD population that increase the probability of developing LiD.

Design setting and Participants

We performed survival analyses to study the development of LiD in 5 separate longitudinal cohorts. We performed a meta-analysis to combine the results of genetic association from each study based on a fixed effects model weighting the effect sizes by the inverse of their standard error. The selection criteria was specific to each cohort. We studied individuals that were genotyped from each cohort and that passed our analysis specific inclusion criteria.

Main Outcomes and Measures

We measured the time for PD patients on levodopa treatment to develop LiD as defined by reaching a score higher or equal than 2 from the MDS-UPDRS part IV, item 1, which is equivalent to a range of 26%-50% of the waking time with dyskinesia. We carried out a genome-wide analysis of the hazard ratio and the association of genome-wide SNPs with the probability of developing LiD using cox proportional hazard models (CPH).

Results

This study included 2,784 PD patients of European ancestry, of whom 14.6% developed LiD. Consistent with previous studies, we found female gender (HR = 1.35, SE = 0.11, P = 0.007) and younger age at onset (HR = 1.8, SE = 0.14, P = 2 × 10 -5 ) to increase the probability of developing LiD. We identified three loci significantly associated with time-to-LiD onset. rs72673189 on chromosome 1 (HR = 2.77, SE = 0.18, P = 1.53 × 10 -8 ) located in the LRP8 locus, rs189093213 on chromosome 4 (HR = 3.06,, SE = 0.19, P = 2.81 × 10 -9 ) in the non-coding RNA LINC02353 locus, and rs180924818 on chromosome 16 (HR = 3.13, SE = 0.20, P = 6.27 × 10 -9 ) in the XYLT1 locus. Subsequent colocalization analyses on chromosome 1 identified DNAJB4 as a candidate gene associated with LiD through a change in gene expression. We computed a PRS based on our GWAS meta-analysis and found high accuracy to stratify between PD-LID and PD (AUC 83.9). We also performed a stepwise regression analysis for baseline features selection associated with LiD status. We found baseline anxiety status to be significantly associated with LiD (OR = 1.14, SE = 0.03, P = 7.4 × 10 -5 ). Finally, we performed a candidate variant analysis and found that genetic variability in ANKK1 ( rs1800497 , Beta = 0.24, SE = 0.09, P = 8.89 × 10 -3 ) and BDNF ( rs6265 , Beta = 0.19, SE = 0.10, P = 4.95 × 10 -2 ) loci were significantly associated with time to LiD in our large meta-analysis.

Conclusion

In this association study, we have found three novel genetic variants associated with LiD, as well as confirming reports that variability in ANKK1 and BDNF loci were significantly associated with LiD probability. A PRS nominated from our time-to-LiD meta-analysis significantly differentiated between PD-LiD and PD. In addition, we have found female gender, young PD onset and anxiety to be significantly associated with LiD.

HLA in isolated REM sleep behavior disorder and Lewy body dementia

Background and Objectives

Isolated/idiopathic REM sleep behavior disorder (iRBD) and Lewy body dementia (LBD) are synucleinopathies that have partial genetic overlap with Parkinson's disease (PD). Previous studies have shown that neuroinflammation plays a substantial role in these disorders. In PD, specific residues of the human leukocyte antigen ( HLA ) were suggested to be associated with a protective effect. This study examined whether the HLA locus plays a similar role in iRBD, LBD and PD.

Methods

We performed HLA imputation on iRBD genotyping data (1,072 patients and 9,505 controls) and LBD whole-genome sequencing (2,604 patients and 4,032 controls) using the multi-ethnic HLA reference panel v2 from the Michigan Imputation Server. Using logistic regression, we tested the association of HLA alleles, amino acids and haplotypes with disease susceptibility. We included age, sex and the top 10 principal components as covariates. We also performed an omnibus test to examine which HLA residue positions explain the most variance.

Results

In iRBD, HLA-DRB1 *11:01 was the only allele passing FDR correction (OR=1.57, 95% CI=1.27-1.93, p =2.70e-05). We also discovered associations between iRBD and HLA-DRB1 70D (OR=1.26, 95%CI=1.12-1.41, p =8.76e-05), 70Q (OR=0.81, 95% CI=0.72-0.91, p =3.65e-04) and 71R (OR=1.21, 95% CI=1.08-1.35, p =1.35e-03). In HLA-DRB1 , position 71 ( p omnibus =0.00102) and 70 ( p omnibus =0.00125) were associated with iRBD. We found no association in LBD.

Discussion

This study identified an association between HLA-DRB1 11:01 and iRBD, distinct from the previously reported association in PD. Therefore, the HLA locus may play different roles across synucleinopathies. Additional studies are required better to understand HLA's role in iRBD and LBD.

NPC1 variants are not associated with Parkinson’s disease, REM-sleep behaviour disorder or Dementia with Lewy bodies in European cohorts

NPC1 encodes a lysosomal protein involved in cholesterol transport. Biallelic mutations in this gene may lead to Niemann-Pick disease type C (NPC), a lysosomal storage disorder. The role of NPC1 in alpha synucleinopathies is still unclear, as different genetic, clinical, and pathological studies have reported contradictory results. This study aimed to evaluate the association of NPC1 variants with the synucleinopathies Parkinson's disease (PD), dementia with Lewy bodies (DLB), and rapid eye movement-sleep behavior disorder (RBD). We analyzed common and rare variants from 3 cohorts of European descent: 1084 RBD cases and 2945 controls, 2852 PD cases and 1686 controls, and 2610 DLB cases and 1920 controls. Logistic regression models were used to assess common variants while optimal sequence Kernel association tests were used to assess rare variants, both adjusted for sex, age, and principal components. No variants were associated with any of the synucleinopathies, supporting that common and rare NPC1 variants do not play an important role in alpha synucleinopathies.

Genome-Wide Association Studies of Cognitive and Motor Progression in Parkinson's Disease

BACKGROUND

There are currently no treatments that stop or slow the progression of Parkinson's disease (PD). Case-control genome-wide association studies have identified variants associated with disease risk, but not progression. The objective of the current study was to identify genetic variants associated with PD progression.

METHODS

We analyzed 3 large longitudinal cohorts: Tracking Parkinson's, Oxford Discovery, and the Parkinson's Progression Markers Initiative. We included clinical data for 3364 patients with 12,144 observations (mean follow-up 4.2 years). We used a new method in PD, following a similar approach in Huntington's disease, in which we combined multiple assessments using a principal components analysis to derive scores for composite, motor, and cognitive progression. These scores were analyzed in linear regression in genome-wide association studies. We also performed a targeted analysis of the 90 PD risk loci from the latest case-control meta-analysis.

RESULTS

There was no overlap between variants associated with PD risk, from case-control studies, and PD age at onset versus PD progression. The APOE ε4 tagging variant, rs429358, was significantly associated with composite and cognitive progression in PD. Conditional analysis revealed several independent signals in the APOE locus for cognitive progression. No single variants were associated with motor progression. However, in gene-based analysis, ATP8B2, a phospholipid transporter related to vesicle formation, was nominally associated with motor progression (P = 5.3 × 10^-6 ).

CONCLUSIONS

We provide early evidence that this new method in PD improves measurement of symptom progression. We show that the APOE ε4 allele drives progressive cognitive impairment in PD. Replication of this method and results in independent cohorts are needed. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Detection of alpha-synuclein conformational variants from gastro-intestinal biopsy tissue as a potential biomarker for Parkinson's disease

Aims

Gastrointestinal (GI) α‐synuclein (aSyn) detection as a potential biomarker of Parkinson's disease (PD) is challenged by conflicting results of recent studies. To increase sensitivity and specificity, we applied three techniques to detect different conformations of aSyn in GI biopsies obtained from a longitudinal, clinically well‐characterized cohort of PD patients and healthy controls (HC).

Methods

With immunohistochemistry (IHC), we used antibodies reactive for total, phosphorylated and oligomeric aSyn; with aSyn proximity ligation assay (AS‐PLA), we targeted oligomeric aSyn species specifically; and with paraffin‐embedded tissue blot (AS‐PET‐blot) we aimed to detect fibrillary, synaptic aSyn.

Results

A total of 163 tissue blocks were collected from 51 PD patients (113 blocks) and 21 HC (50 blocks). In 31 PD patients, biopsies were taken before the PD diagnosis (Prodromal); while in 20 PD patients biopsies were obtained after diagnosis (Manifest). The majority of tissues blocks were from large intestine (62%), followed by small intestine (21%), stomach (10%) and oesophagus (7%). With IHC, four staining patterns were detected (neuritic, ganglionic, epithelial and cellular), while two distinct staining patterns were detected both with AS‐PLA (cellular and diffuse signal) and with AS‐PET‐blot (aSyn‐localized and pericrypt signal). The level of agreement between different techniques was low and no single technique or staining pattern reliably distinguished PD patients (Prodromal or Manifest) from HC.

Conclusions

Our study suggests that detection of aSyn conformational variants currently considered pathological is not adequate for the diagnosis or prediction of PD. Future studies utilizing novel ultrasensitive amyloid aggregation assays may increase sensitivity and specificity.

Cortical structural involvement and cognitive dysfunction in early Parkinson's disease

Magnetic resonance imaging (MRI) studies in early Parkinson's disease (PD) have shown promise in the detection of disease-related brain changes in the white and deep grey matter. We set out to establish whether intrinsic cortical involvement in early PD can be detected with quantitative MRI. We collected a rich, multi-modal dataset, including diffusion MRI, T₁ relaxometry and cortical morphometry, in 20 patients with early PD (disease duration, 1.9 ± 0.97 years, Hoehn & Yahr 1-2) and in 19 matched controls. The cortex was reconstructed using FreeSurfer. Data analysis employed linked independent component analysis (ICA), a novel data-driven technique that allows for data fusion and extraction of multi-modal components before further analysis. For comparison, we performed standard uni-modal analysis with a general linear model (GLM). Linked ICA detected multi-modal cortical changes in early PD (p = 0.015). These comprised fractional anisotropy reduction in dorsolateral prefrontal, cingulate and premotor cortex and the superior parietal lobule, mean diffusivity increase in the mesolimbic, somatosensory and superior parietal cortex, sparse diffusivity decrease in lateral parietal and right prefrontal cortex, and sparse changes to the cortex area. In PD, the amount of cortical dysintegrity correlated with diminished cognitive performance. Importantly, uni-modal analysis detected no significant group difference on any imaging modality. We detected microstructural cortical pathology in early PD using a data-driven, multi-modal approach. This pathology is correlated with diminished cognitive performance. Our results indicate that early degenerative processes leave an MRI signature in the cortex of patients with early PD. The cortical imaging findings are behaviourally meaningful and provide a link between cognitive status and microstructural cortical pathology in patients with early PD.

Validation of conversion between mini-mental state examination and montreal cognitive assessment

INTRODUCTION

Harmonizing data across cohorts is important for validating findings or combining data in meta-analyses. We replicate and validate a previous conversion of MoCA to MMSE in PD.

METHODS

We used five studies with 1,161 PD individuals and 2,091 observations measured with both the MoCA and MMSE. We compared a previously published conversion table using equipercentile equating with log-linear smoothing to our internally derived scores.

RESULTS

Both conversions found good agreement within and across the studies when comparing true and converted MMSE (mean difference: 0.05; standard deviation: 1.84; median difference: 0; interquartile range: -1 to 1, using internal conversion).

CONCLUSIONS

These results show that one can get a reliable and valid conversion between two commonly used measures of cognition in PD studies. These approaches need to be applied to other scales and domains to enable large-scale collaborative analyses across multiple PD cohorts.

Motorcycle emissions and fuel consumption in urban and rural driving conditions

This work reports sampling of motorcycle on-road driving cycles in actual urban and rural environments and the development of representative driving cycles using the principle of least total variance in individual regions. Based on the representative driving cycles in individual regions, emission factors for carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO(x)=NO+NO(2)) and carbon dioxide (CO(2)), as well as fuel consumption, were determined using a chassis dynamometer. The measurement results show that the representative driving cycles are almost identical in the three largest cities in Taiwan, but they differ significantly from the rural driving cycle. Irrespective of driving conditions, emission factors differ insignificantly between the urban and rural regions at a 95% confidence level. However, the fuel consumption in urban centers is approximately 30% higher than in the rural regions, with driving conditions in the former usually poor compared to the latter. Two-stroke motorcycles generally have considerably higher HC emissions and quite lower NO(x) emissions than those of four-stroke motorcycles. Comparisons with other studies suggest that factors such as road characteristics, traffic volume, vehicle type, driving conditions and driver behavior may affect motorcycle emission levels in real traffic situations.

Correlating rates of cerebral atrophy in Parkinson's disease with measures of cognitive decline

We studied eight clinically non-demented PD patients and ten age-matched controls with serial volumetric T1-weighted MRI. All PD patients underwent full neuropsychological testing at baseline and follow up scans. Sub-voxel coregistration of the serial MRI scans with quantification of changes in total brain substance and ventricular size per year was performed. The PD patients had significant reductions in both percentage and absolute annual brain volume loss when compared to age-matched controls (p < 0.001). There were significant correlations between reductions in percentage brain volume loss and estimated reductions in performance IQ (r = 0.841, p = 0.004) and full scale IQ (r = 0.63, p = 0.049), measured by subtracting IQ measures at time of follow up scan from premorbid estimates. In conclusion, PD patients have a significant rate of median brain volume loss [10.35 (range) 6.69-16.90 ml/year] with no significant loss seen in age-matched controls, and these changes correlate with global measures of cognitive decline. Further longitudinal studies could evaluate whether serial volumetric MRI is a useful technique in predicting the preclinical onset of dementia in Parkinson's disease patients, and its role in the assessment of putative treatments for slowing disease progression.

A comparison of (18)F-dopa PET and inversion recovery MRI in the diagnosis of Parkinson's disease

OBJECTIVE

To quantify structural changes in the substantia nigra of patients with PD with inversion recovery MRI and to compare these with striatal dopaminergic function measured with (18)F-dopa PET.

METHODS

The authors studied 10 patients with PD and eight age-matched control subjects with a combination of MR sequences previously reported to be sensitive to nigral cell loss. Striatal regions of interest were defined on T1-weighted MRI coregistered to (18)F-dopa PET in all subjects.

RESULTS

Discriminant function analysis of the quantified MR nigral signal correctly classified 83% of the combined PD patient/control group; three of 10 PD cases were incorrectly classified as "normal" (Wilks' lambda = 0.724, p > 0.05). Discriminant function analysis correctly classified 100% of PD patients and control subjects with (18)F-dopa PET based on mean caudate and putamen K(i) values (Wilks' lambda = 0.065, p < 0.001). Correlations between mean putamen K(i) and rostral and caudal nigral MR signal changes and mean caudate K(i) and caudal nigral MR signal changes were found (r = -0.76, -0.69, -0.80, p < 0.05).

CONCLUSION

(18)F-dopa PET is more reliable than inversion recovery MRI in discriminating patients with moderately severe PD from normal subjects. However, the structural changes detected within the substantia nigra of patients with PD found using inversion recovery MRI correlate with measures of striatal dopaminergic function using (18)F-dopa PET.

Cortical dysfunction in non-demented Parkinson's disease patients: a combined (31)P-MRS and (18)FDG-PET study

Regional cerebral phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) was performed in 10 non- demented Parkinson's disease patients and nine age-matched control subjects. Five of the patients undergoing (31)P-MRS and four additional Parkinson's disease patients had cerebral 2-[(18)F]fluoro-2-deoxy-D-glucose PET ((18)FDG-PET), the results of which were compared with those of eight age-matched control subjects. All Parkinson's disease patients underwent neuropsychological testing including performance and verbal subtests of the Wechsler Adult Intelligence Scale-Revised, Boston Naming Test, Controlled Oral Word Association test (FAS Test) and California Learning Test to exclude clinical dementia. (31)P MR spectra from right and left temporo-parietal cortex, occipital cortex and a central voxel incorporating basal ganglia and brainstem were obtained. (31)P MR peak area ratios of signals from phosphomonoesters (PMEs), inorganic phosphate (P(i)), phosphodiesters (PDEs), alpha-ATP, gamma-ATP and phosphocreatine (PCr) relative to beta-ATP were measured. Relative percentage peak areas of PMEs, P(i), PDEs, PCr, and alpha-, beta- and gamma-ATP signals were also measured with respect to the total (31)P-MRS signal. Significant bilateral increases in the P(i)/beta-ATP ratio were found in temporoparietal cortex (P = 0.002 right and P = 0.014 left cortex) for the non-demented Parkinson's disease patients compared with controls. In the right temporoparietal cortex, there was also a significant increase in the mean relative percentage P(i) (P = 0.001). (18)FDG-PET revealed absolute bilateral reductions in glucose metabolism after partial volume effect correction in posterior parietal and temporal cortical grey matter (P < 0.01 and P < 0.05, respectively) for the Parkinson's disease group, using both volume of interest analysis and statistical parametric mapping. There were significant correlations between right temporoparietal P(i)/beta-ATP ratios and estimated reductions in performance IQ (r = 0.96, P < 0.001). Left temporoparietal P(i)/beta-ATP ratios correlated with full scale IQ and verbal IQ (r = -0.82, P = 0.006, r = -0.86, P = 0.003, respectively). In summary, temporoparietal cortical hypometabolism was seen in non-demented Parkinson's disease patients with both (31)P-MRS and (18)FDG-PET, suggesting that both glycolytic and oxidative pathways are impaired. This dysfunction may reflect either the presence of primary cortical pathology or deafferentation of striato-cortical projections. (31)P-MRS and (18)FDG-PET may both provide useful predictors of future cognitive impairment in a subset of Parkinson's disease patients who go on to develop dementia.

Late onset levodopa responsive Huntington's disease with minimal chorea masquerading as Parkinson plus syndrome

Huntington's disease is characterised by hyperkinetic movements, mainly chorea, cognitive dysfunction, and psychiatric abnormalities. Non-dopa responsive parkinsonism occurs in the later stages of choreic disease or as the predominant feature of juvenile patients (Westphal variant). Late onset Huntington's disease presenting as levodopa responsive parkinsonism is rare. A series of four patients with late onset Huntington's disease presenting as levodopa responsive parkinsonism and cardiovascular dysautonomia, initially misdiagnosed as multiple system atrophy (MSA) in three patients, is reported. Levodopa treatment did not unmask significant chorea. These cases suggest the presence of a distinct phenotypic variant of Huntington's disease to be added to the differential diagnosis of other akinetic rigid syndromes.

Atypical parkinsonism in Afro-Caribbean and Indian origin immigrants to the UK

This article reviews evidence for the occurrence of atypical parkinsonism in Afro-Caribbean and Indian ethnic minority subjects living in western countries, particularly the UK. Current information on the frequency, pattern, and prevalence of Parkinson's disease and parkinsonism in these communities is unclear and controversial. While several workers have suggested that there is a low prevalence of Parkinson's disease in populations of African origin, other workers have suggested a higher prevalence of Parkinson's disease in African Americans. Furthermore, little information is available in relation to the pattern of parkinsonism in these subjects. A recent phenomenologic study of parkinsonism in the French West Indies by Caparros-Lefebvre and colleagues has indicated a significantly increased frequency of atypical parkinsonism in local non-white subjects. Since 1995, we have been studying the pattern and frequency of parkinsonism in Afro-Caribbean and Indian (originating from the Indian subcontinent) patients living in the UK, with London serving as the coordinating center. Our results indicate that there is a three- to fourfold increase in the frequency of occurrence of sporadic atypical parkinsonism characterized by levodopa hyporesponsiveness, bradykinesia-dominant disease, and early cognitive dysfunction in these patients even after exclusion of patients with clinically probable multiple system atrophy, progressive supranuclear palsy, and Lewy body dementia. These findings are similar to observations made in the French West Indies. Ongoing studies in India suggest that atypical parkinsonism also affects local patients, and the pattern of parkinsonism tends to differ from Afro-Caribbean subjects in the UK. Studies are currently underway to unravel the mechanism of increased frequency of atypical parkinsonism in these ethnic groups and include genetic studies addressing polymorphisms of enzymes metabolizing levodopa, dietary neurotoxin screen and functional imaging studies of the striatum using positron emission tomography. Furthermore, the contribution of diabetes mellitus and hypertension, commonly seen in these ethnic groups, is also being examined.

Limb contractures in levodopa-responsive parkinsonism: a clinical and investigational study of seven new cases

We describe six patients with classical levodopa-responsive Parkinson's disease (PD) and one case of levodopa-responsive familial juvenile dystonia-parkinsonism with fixed contractures of the hands, feet or legs. In most patients contractures became established over a short period (2 months-2 years) but a considerable time after onset of parkinsonism (mean 13 years). Mean disease duration was 17 years, and all patients had severe levodopa-induced dyskinesias, either biphasic or peak dose, in the affected limb prior to onset of the contracture. Nerve conduction studies excluded peripheral ulnar nerve lesions in all patients with one exception, who was found to have a mild bilateral ulnar entrapment neuropathy. Transcranial magnetic stimulation performed in five of the seven patients showed shorter mean central motor conduction time in the affected than in the unaffected limb. Results of magnetic resonance imaging of the brain performed in a subgroup of patients were normal, with no evidence to suggest multiple system atrophy, cerebral infarction or focal abnormalities of the basal ganglia. We conclude that hand and feet contractures are not necessarily restricted to parkinson plus syndromes and may complicate otherwise typical PD in the absence of a structural or peripheral nervous cause. Striatal dopaminergic deficiency, particularly long-standing, may have a role in the pathogenesis of limb contractures in PD.

Evidence for cortical dysfunction in clinically non-demented patients with Parkinson's disease: a proton MR spectroscopy study

OBJECTIVES

To investigate whether proton magnetic resonance spectroscopy (1H MRS) can detect cortical dysfunction in non-demented patients with Parkinson's disease, and to correlate changes with cognitive function on formal neuropsychological testing.

METHODS

Multivoxel 1H MRS was performed in 17 patients with levodopa treated idiopathic Parkinson's disease with out clinical dementia, and 10 age match ed control subjects. Measurements of N-acetylaspartate (NAA)/choline (Cho), NAA/creatine+phosphocreatine (Cr), and Cho/Cr were obtained from right and left temporoparietal cortex and occipital cortex. Fourteen patients with Parkinson's disease underwent a full battery of neuropsychological testing including performance and verbal subtests of the WAIS-R, Boston naming test, FAS test, and California verbal learning test.

RESULTS

There were significant temporoparietal cortex reductions in NAA/Cr ratios in right and left averaged spectra of the patients with Parkinson's disease (p=0.012 after Bonferroni correction) and in spectra contralateral to the worst clinically affected limbs of the patients with Parkinson's disease compared with controls (p = 0.003 after Bonferroni correction). There was a significant correlation between reduction in NAA/Cr ratios and measures of global cognitive decline, occurring independently of motor impairment (p=0.019).

CONCLUSIONS

This study suggests that 1H MRS can detect temporoparietal cortical dysfunction in non-demented patients with Parkinson's disease. Further longitudinal studies are needed to investigate whether these 1H MRS changes are predictive of future cognitive impairment in the subset of patients with Parkinson's disease who go on to develop dementia, or occur as part of the normal Parkinson's disease process.

Acute sciatica with an infective cause

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