Cognitive Impairment Is Part of the Phenotype of Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS)

BACKGROUND

Little is known about the impact of the cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) on cognition.

OBJECTIVE

Our objective was to determine the frequency and severity of cognitive impairment in RFC1-positive patients and describe the pattern of deficits.

METHODS

Participants underwent a comprehensive neuropsychological assessment. Volume of the cerebellum and its lobules was measured in those who underwent a 3 Tesla-magnetic resonance scan.

RESULTS

Twenty-one patients underwent a complete assessment, including 71% scoring lower than the cutoff at the Montreal Cognitive assessment and 71% having a definite cerebellar cognitive affective/Schmahmann syndrome. Three patients had dementia and seven met the criteria of mild cognitive impairment. Severity of cognitive impairment did not correlate with severity of clinical manifestations. Performance at memory and visuospatial functions tests negatively correlated with the severity of cerebellar manifestations.

CONCLUSION

Cognitive manifestations are frequent in RFC1-related disorders. They should be included in the phenotype and screened systematically. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Investigation of Shared Genetic Risk Factors Between Parkinson's Disease and Cancers

BACKGROUND

Epidemiological studies that examined the association between Parkinson's disease (PD) and cancers led to inconsistent results, but they face a number of methodological difficulties.

OBJECTIVE

We used results from genome-wide association studies (GWASs) to study the genetic correlation between PD and different cancers to identify common genetic risk factors.

METHODS

We used individual data for participants of European ancestry from the Courage-PD (Comprehensive Unbiased Risk Factor Assessment for Genetics and Environment in Parkinson's Disease; PD, N = 16,519) and EPITHYR (differentiated thyroid cancer, N = 3527) consortia and summary statistics of GWASs from iPDGC (International Parkinson Disease Genomics Consortium; PD, N = 482,730), Melanoma Meta-Analysis Consortium (MMAC), Breast Cancer Association Consortium (breast cancer), the Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome (prostate cancer), International Lung Cancer Consortium (lung cancer), and Ovarian Cancer Association Consortium (ovarian cancer) (N comprised between 36,017 and 228,951 for cancer GWASs). We estimated the genetic correlation between PD and cancers using linkage disequilibrium score regression. We studied the association between PD and polymorphisms associated with cancers, and vice versa, using cross-phenotypes polygenic risk score (PRS) analyses.

RESULTS

We confirmed a previously reported positive genetic correlation of PD with melanoma (Gcorr = 0.16 [0.04; 0.28]) and reported an additional significant positive correlation of PD with prostate cancer (Gcorr = 0.11 [0.03; 0.19]). There was a significant inverse association between the PRS for ovarian cancer and PD (odds ratio [OR] = 0.89 [0.84; 0.94]). Conversely, the PRS of PD was positively associated with breast cancer (OR = 1.08 [1.06; 1.10]) and inversely associated with ovarian cancer (OR = 0.95 [0.91; 0.99]). The association between PD and ovarian cancer was mostly driven by rs183211 located in an intron of the NSF gene (17q21.31).

CONCLUSIONS

We show evidence in favor of a contribution of pleiotropic genes to the association between PD and specific cancers. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Indication for molecular testing by multiplex ligation-dependent probe amplification in parkinsonism

BACKGROUND

The monogenic forms of Parkinson's disease represent less than 10% of familial cases and a still lower frequency of sporadic cases. However, guidelines to orient genetic testing are lacking. We aim to establish the interest of multiplex ligation-dependent probe amplification as a primary screening test and to propose clinical criteria to guide genetic diagnostic tests for patients with suspected Mendelian Parkinson's disease.

METHODS

We recruited 567 patients with parkinsonism from 547 unrelated families and performed two multiplex ligation-dependent probe amplifications for each. We confirmed all pathogenic G2019S variants in the LRRK2 gene by Sanger sequencing and screened the PRKN gene for a second mutation in cases of one heterozygous structural variant in the PRKN gene.

RESULTS

The performance of multiplex ligation-dependent probe amplifications was 51/567 (9%) for the entire cohort and included 27 (4.8%) LRRK2 G2019S mutations, 19 (3.4%) PRKN mutations, and 5 (0.9%) SNCA locus duplications. The variables significantly associated with a positive test in the total cohort were North African ancestry (p < 0.0001), female sex (p = 0.004), and younger age at onset (p < 0.0008).

CONCLUSIONS

Retrospective analysis allowed us to refine our indication criteria: (i) North African ancestry, (ii) an age at onset < 40, or (iii) a familial history of parkinsonism with at least one affected first-degree relative. Our study highlights the interest of MLPA testing for other parkinsonisms cases with a family history, especially for patients with dementia with Lewy bodies or a multiple system atrophy-like phenotype.

The Interaction between HLA-DRB1 and Smoking in Parkinson's Disease Revisited

BACKGROUND

Two studies that examined the interaction between HLA-DRB1 and smoking in Parkinson's disease (PD) yielded findings in opposite directions.

OBJECTIVE

To perform a large-scale independent replication of the HLA-DRB1 × smoking interaction.

METHODS

We genotyped 182 single nucleotide polymorphism (SNPs) associated with smoking initiation in 12 424 cases and 9480 controls to perform a Mendelian randomization (MR) analysis in strata defined by HLA-DRB1.

RESULTS

At the amino acid level, a valine at position 11 (V11) in HLA-DRB1 displayed the strongest association with PD. MR showed an inverse association between genetically predicted smoking initiation and PD only in absence of V11 (odds ratio, 0.74, 95% confidence interval, 0.59-0.93, PInteraction  = 0.028). In silico predictions of the influence of V11 and smoking-induced modifications of α-synuclein on binding affinity showed findings consistent with this interaction pattern.

CONCLUSIONS

Despite being one of the most robust findings in PD research, the mechanisms underlying the inverse association between smoking and PD remain unknown. Our findings may help better understand this association. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Use of levodopa-carbidopa intestinal gel to treat patients with multiple system atrophy

BACKGROUND

Levodopa-carbidopa intestinal gel (LCIG) is an effective treatment for late-stage Parkinson's disease (PD) but had not been evaluated in levodopa-responsive patients with the parkinsonian variant of multiple system atrophy (MSA-P) and motor fluctuations. We aimed to assess the safety of LCIG in MSA-P patients.

METHODS

In a retrospective, single-center study, we analyzed clinical and treatment-related data for all patients with MSA-P or PD treated with LCIG between December 2004 and November 2017. Adverse events (AEs) were classified into three classes: AEs related to gastrointestinal effects or to the PEG-J procedure, AEs related to the device, and AEs related to the pharmacological effect of LCIG.

RESULTS

7 MSA-P and 63 PD patients had been treated with LCIG for a median [interquartile range] period of 31 [16;43] and 19 [8;45] months, respectively. There were no significant intergroup differences in safety. Enteral nutrition was introduced at the same time as LCIG treatment in 4 (57%) MSA-P patients. In the MSA-P and PD groups, LCIG was associated with a better Global Clinical Impression score and discontinuation of oral anti-parkinsonian drugs (in 43% and 27% of cases, respectively).

CONCLUSIONS

LCIG treatment is feasible in MSA-P patients with severe motor complications. The safety profile is similar to that seen in PD.

Functional Analyses of Two Novel LRRK2 Pathogenic Variants in Familial Parkinson's Disease

Background

Pathogenic variants in the LRRK2 gene are a common monogenic cause of Parkinson's disease. However, only seven variants have been confirmed to be pathogenic.

Objectives

We identified two novel LRRK2 variants (H230R and A1440P) and performed functional testing.

Methods

We transiently expressed wild‐type, the two new variants, or two known pathogenic mutants (G2019S and R1441G) in HEK‐293 T cells, with or without LRRK2 kinase inhibitor treatment. We characterized the phosphorylation and kinase activity of the mutants by western blotting. Thermal shift assays were performed to determine the folding and stability of the LRRK2 proteins.

Results

The two variants were found in two large families and segregate with the disease. They display altered LRRK2 phosphorylation and kinase activity.

Conclusions

We identified two novel LRRK2 variants which segregate with the disease. The results of functional testing lead us to propose these two variants as novel causative mutations for familial Parkinson's disease. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Dairy Intake and Parkinson's Disease: A Mendelian Randomization Study

BACKGROUND

Previous prospective studies highlighted dairy intake as a risk factor for Parkinson's disease (PD), particularly in men. It is unclear whether this association is causal or explained by reverse causation or confounding.

OBJECTIVE

The aim is to examine the association between genetically predicted dairy intake and PD using two-sample Mendelian randomization (MR).

METHODS

We genotyped a well-established instrumental variable for dairy intake located in the lactase gene (rs4988235) within the Courage-PD consortium (23 studies; 9823 patients and 8376 controls of European ancestry).

RESULTS

Based on a dominant model, there was an association between genetic predisposition toward higher dairy intake and PD (odds ratio [OR] per one serving per day = 1.70, 95% confidence interval = 1.12-2.60, P = 0.013) that was restricted to men (OR = 2.50 [1.37-4.56], P = 0.003; P-difference with women = 0.029).

CONCLUSIONS

Using MR, our findings provide further support for a causal relationship between dairy intake and higher PD risk, not biased by confounding or reverse causation. Further studies are needed to elucidate the underlying mechanisms. © 2022 International Parkinson and Movement Disorder Society.

Does ultrasound-guidance improve the outcome of botulinum toxin injections in cervical dystonia?

PURPOSE

Ultrasound-guided injections of botulinum neurotoxin in cervical dystonia have a number of theoretical advantages. However, their action has never been compared to that of non-guided injections. The objectives of the study were to compare the outcome of botulinum neurotoxin type A treatment in patients with idiopathic, focal cervical dystonia, according to two methods: inspection and palpation of anatomical landmarks (non-guided group) or ultrasound guidance (ultrasound-guided group).

METHODS

We included consecutive patients in this single-center, prospective, real-life, non-randomized study. The outcomes were evaluated one month after the injections: Cervical Dystonia Impact Profile 58 (main outcome), Toronto Western Spasmodic Torticollis Rating Scale-2 (pain and disability subscores), Toronto Western Spasmodic Torticollis Rating Scale-PSYCH, patient-rated Clinical Global Impression - Improvement and adverse events. We used propensity score methods for statistical analysis; ten predefined confounding factors were used to build the propensity score.

RESULTS

Sixty-three patients were included in the non-guided group, and 60 other patients in the ultrasound-guided group. We found no difference in main and secondary outcomes between the two study groups.

CONCLUSION

This is the first direct comparison between ultrasound-guided and non-guided botulinum neurotoxin type A injections in patients with cervical dystonia. We hypothesize that ultrasound guidance made it possible to obtain the same results in the most severe (or the most demanding) patients as in the best responders. Further studies are still needed to assess the impact of botulinum neurotoxin injections into deep cervical muscles.

Mendelian Randomisation Study of Smoking, Alcohol, and Coffee Drinking in Relation to Parkinson's Disease

BACKGROUND

Previous studies showed that lifestyle behaviors (cigarette smoking, alcohol, coffee) are inversely associated with Parkinson's disease (PD). The prodromal phase of PD raises the possibility that these associations may be explained by reverse causation.

OBJECTIVE

To examine associations of lifestyle behaviors with PD using two-sample Mendelian randomisation (MR) and the potential for survival and incidence-prevalence biases.

METHODS

We used summary statistics from publicly available studies to estimate the association of genetic polymorphisms with lifestyle behaviors, and from Courage-PD (7,369 cases, 7,018 controls; European ancestry) to estimate the association of these variants with PD. We used the inverse-variance weighted method to compute odds ratios (ORIVW) of PD and 95%confidence intervals (CI). Significance was determined using a Bonferroni-corrected significance threshold (p = 0.017).

RESULTS

We found a significant inverse association between smoking initiation and PD (ORIVW per 1-SD increase in the prevalence of ever smoking = 0.74, 95%CI = 0.60-0.93, p = 0.009) without significant directional pleiotropy. Associations in participants ≤67 years old and cases with disease duration ≤7 years were of a similar size. No significant associations were observed for alcohol and coffee drinking. In reverse MR, genetic liability toward PD was not associated with smoking or coffee drinking but was positively associated with alcohol drinking.

CONCLUSION

Our findings are in favor of an inverse association between smoking and PD that is not explained by reverse causation, confounding, and survival or incidence-prevalence biases. Genetic liability toward PD was positively associated with alcohol drinking. Conclusions on the association of alcohol and coffee drinking with PD are hampered by insufficient statistical power.

Severe Phenotype in Patients with Large Deletions of NF1

Complete deletion of the NF1 gene is identified in 5-10% of patients with neurofibromatosis type 1 (NF1). Several studies have previously described particularly severe forms of the disease in NF1 patients with deletion of the NF1 locus, but comprehensive descriptions of large cohorts are still missing to fully characterize this contiguous gene syndrome. NF1-deleted patients were enrolled and phenotypically characterized with a standardized questionnaire between 2005 and 2020 from a large French NF1 cohort. Statistical analyses for main NF1-associated symptoms were performed versus an NF1 reference population. A deletion of the NF1 gene was detected in 4% (139/3479) of molecularly confirmed NF1 index cases. The median age of the group at clinical investigations was 21 years old. A comprehensive clinical assessment showed that 93% (116/126) of NF1-deleted patients fulfilled the NIH criteria for NF1. More than half had café-au-lait spots, skinfold freckling, Lisch nodules, neurofibromas, neurological abnormalities, and cognitive impairment or learning disabilities. Comparison with previously described "classic" NF1 cohorts showed a significantly higher proportion of symptomatic spinal neurofibromas, dysmorphism, learning disabilities, malignancies, and skeletal and cardiovascular abnormalities in the NF1-deleted group. We described the largest NF1-deleted cohort to date and clarified the more severe phenotype observed in these patients.

Mind the Gap: LRRK2 Phenotypes in the Clinic vs. in Patient Cells

Mutations in the Parkinson's disease (PD) protein Leucine Rich Repeat Kinase 2 (LRRK2) have been under study for more than 15 years and our understanding of the cellular phenotypes for the pathogenic mutant forms of LRRK2 has significantly advanced. In parallel to research on LRRK2 mutations in experimental systems, clinical characterization of patients carrying LRRK2 mutations has advanced, as has the analysis of cells that are derived from these patients, including fibroblasts, blood-derived cells, or cells rendered pluripotent. Under the hypothesis that patient clinical phenotypes are a consequence of a cascade of underlying molecular mechanisms gone astray, we currently have a unique opportunity to compare findings from patients and patient-derived cells to ask the question of whether the clinical phenotype of LRRK2 Parkinson's disease and cellular phenotypes of LRRK2 patient-derived cells may be mutually informative. In this review, we aim to summarize the available information on phenotypes of LRRK2 mutations in the clinic, in patient-derived cells, and in experimental models in order to better understand the relationship between the three at the molecular and cellular levels and identify trends and gaps in correlating the data.

Anatomy-guided injections of botulinum neurotoxin in neck muscles: how accurate is needle placement?

BACKGROUND AND PURPOSE

In cervical dystonia, the accuracy of botulinum neurotoxin (BoNT) injections may influence the response to the treatment.

METHODS

We used ultrasound to evaluate the accuracy of anatomy-guided injections of BoNT in the neck muscles.

RESULTS

A total of 56 consecutive patients and 332 injections were evaluated. The overall accuracy was 76.6%. The lowest accuracy (67.9%) was observed for the splenius capitis muscle.

CONCLUSIONS

Anatomic guidance of BoNT injections in the neck muscles is often inaccurate. Imaging guidance may improve the accuracy of BoNT injections in cervical dystonia.

Transcriptomic signatures of brain regional vulnerability to Parkinson's disease

The molecular mechanisms underlying caudal-to-rostral progression of Lewy body pathology in Parkinson's disease remain poorly understood. Here, we identified transcriptomic signatures across brain regions involved in Braak Lewy body stages in non-neurological adults from the Allen Human Brain Atlas. Among the genes that are indicative of regional vulnerability, we found known genetic risk factors for Parkinson's disease: SCARB2, ELOVL7, SH3GL2, SNCA, BAP1, and ZNF184. Results were confirmed in two datasets of non-neurological subjects, while in two datasets of Parkinson's disease patients we found altered expression patterns. Co-expression analysis across vulnerable regions identified a module enriched for genes associated with dopamine synthesis and microglia, and another module related to the immune system, blood-oxygen transport, and endothelial cells. Both were highly expressed in regions involved in the preclinical stages of the disease. Finally, alterations in genes underlying these region-specific functions may contribute to the selective regional vulnerability in Parkinson's disease brains.

Overexpression of Wild-Type Human Alpha-Synuclein Causes Metabolism Abnormalities in Thy1-aSYN Transgenic Mice

Parkinson’s disease is a progressive neurodegenerative disorder characterized by loss of dopaminergic neurons, pathological accumulation of alpha-synuclein and motor symptoms, but also by non-motor symptoms. Metabolic abnormalities including body weight loss have been reported in patients and could precede by several years the emergence of classical motor manifestations. However, our understanding of the pathophysiological mechanisms underlying body weight loss in PD is limited. The present study investigated the links between alpha-synuclein accumulation and energy metabolism in transgenic mice overexpressing Human wild-type (WT) alpha-synuclein under the Thy1 promoter (Thy1-aSYN mice). Results showed that Thy1-aSYN mice gained less body weight throughout life than WT mice, with significant difference observed from 3 months of age. Body composition analysis of 6-month-old transgenic animals showed that body mass loss was due to lower adiposity. Thy1-aSYN mice displayed lower food consumption, increased spontaneous activity, as well as a reduced energy expenditure compared to control mice. While no significant change in glucose or insulin responses were observed, Thy1-aSYN mice had significantly lower plasmatic levels of insulin and leptin than control animals. Moreover, the pathological accumulation of alpha-synuclein in the hypothalamus of 6-month-old Thy1-aSYN mice was associated with a down-regulation of the phosphorylated active form of the signal transducer and activator of transcription 3 (STAT3) and of Rictor (the mTORC2 signaling pathway), known to couple hormonal signals with the maintenance of metabolic and energy homeostasis. Collectively, our results suggest that (i) metabolic alterations are an important phenotype of alpha-synuclein overexpression in mice and that (ii) impaired STAT3 activation and mTORC2 levels in the hypothalamus may underlie the disruption of feeding regulation and energy metabolism in Thy1-aSYN mice.

Typical features of Parkinson disease and diagnostic challenges with microdeletion 22q11.2

OBJECTIVE

To delineate the natural history, diagnosis, and treatment response of Parkinson disease (PD) in individuals with 22q11.2 deletion syndrome (22q11.2DS), and to determine if these patients differ from those with idiopathic PD.

METHODS

In this international observational study, we characterized the clinical and neuroimaging features of 45 individuals with 22q11.2DS and PD (mean follow-up 7.5 ± 4.1 years).

RESULTS

22q11.2DS PD had a typical male excess (32 male, 71.1%), presentation and progression of hallmark motor symptoms, reduced striatal dopamine transporter binding with molecular imaging, and initial positive response to levodopa (93.3%). Mean age at motor symptom onset was relatively young (39.5 ± 8.5 years); 71.4% of cases had early-onset PD (<45 years). Despite having a similar age at onset, the diagnosis of PD was delayed in patients with a history of antipsychotic treatment compared with antipsychotic-naive patients (median 5 vs 1 year, p = 0.001). Preexisting psychotic disorders (24.5%) and mood or anxiety disorders (31.1%) were common, as were early dystonia (19.4%) and a history of seizures (33.3%).

CONCLUSIONS

Major clinical characteristics and response to standard treatments appear comparable in 22q11.2DS-associated PD to those in idiopathic PD, although the average age at onset is earlier. Importantly, treatment of preexisting psychotic illness may delay diagnosis of PD in 22q11.DS patients. An index of suspicion and vigilance for complex comorbidity may assist in identifying patients to prioritize for genetic testing.

RNA-binding disturbances as a continuum from spinocerebellar ataxia type 2 to Parkinson disease

CAG triplet expansions in Ataxin-2 gene (ATXN2) cause spinocerebellar ataxia type 2 and have a role that remains to be clarified in Parkinson's disease (PD). To study the molecular events associated with these expansions, we sequenced them and analyzed the transcriptome from blood cells of controls and three patient groups diagnosed with spinocerebellar ataxia type 2 (herein referred to as SCA2c) or PD with or without ATXN2 triplet expansions (named SCA2p). The transcriptome profiles of these 40 patients revealed three main observations: i) a specific pattern of pathways related to cellular contacts, proliferation and differentiation associated with SCA2p group, ii) similarities between the SCA2p and sporadic PD groups in genes and pathways known to be altered in PD such as Wnt, Ephrin and Leukocyte extravasation signaling iii) RNA metabolism disturbances with "RNA-binding" and "poly(A) RNA-binding" as a common feature in all groups. Remarkably, disturbances of ALS signaling were shared between SCA2p and sporadic PD suggesting common molecular dysfunctions in PD and ALS including CACNA1, hnRNP, DDX and PABPC gene family perturbations. Interestingly, the transcriptome profiles of patients with parkinsonian phenotypes were prevalently associated with alterations of translation while SCA2c and PD patients presented perturbations of splicing. While ATXN2 RNA expression was not perturbed, its protein expression in immortalized lymphoblastoid cells was significantly decreased in SCA2c and SCA2p versus control groups assuming post-transcriptional biological perturbations. In conclusion, the transcriptome data do not exclude the role of ATXN2 mutated alleles in PD but its decrease protein expression in both SCA2c and SCA2p patients suggest a potential involvement of this gene in PD. The perturbations of "RNA-binding" and "poly(A) RNA-binding" molecular functions in the three patient groups as well as gene deregulations of factors not yet described in PD but known to be deleterious in other neurological conditions, suggest the existence of RNA-binding disturbances as a continuum between spinocerebellar ataxia type 2 and Parkinson's disease.

A randomized, controlled, double-blind, crossover trial of zonisamide in myoclonus-dystonia

OBJECTIVE

To evaluate the efficacy and safety of zonisamide in patients with myoclonus-dystonia.

METHODS

We conducted a randomized, double-blind, placebo-controlled crossover trial of zonisamide (300 mg/d) in 24 patients with myoclonus-dystonia. Each treatment period consisted of a 6-week titration phase followed by a 3-week fixed-dose phase. The periods were separated by a 5-week washout period. The co-primary outcomes were action myoclonus severity (section 4 of the Unified Myoclonus Rating Scale [UMRS 4]) and myoclonus-related functional disability (UMRS 5). Secondary outcomes included dystonia severity, assessed with the movement and disability subscales of the Burke-Fahn-Marsden-Dystonia Rating Scale (BFM), the Clinical Global Impression-Improvement scale (CGI), and safety measures. Wilcoxon signed-rank tests for paired data were used to analyze treatment effects.

RESULTS

Twenty-three patients (11 men, 12 women) were analyzed in the intention-to-treat analysis. Zonisamide significantly improved both action myoclonus (median improvement [95% confidence limits] -5 [-9.25 to -1.44], p = 0.003) and myoclonus-related functional disability (median improvement [95% confidence limits] -2 [-2.58 to -2.46], p = 0.007) compared to placebo. Zonisamide also significantly improved dystonia (BFM movement) compared to placebo (median improvement [95% confidence limits] -3 [-8.46 to 0.03], p = 0.009). No difference was found between zonisamide and placebo with respect to the CGI (median improvement [95% confidence limits] -1 [-1.31 to 0.09], p = 0.1). Zonisamide was well-tolerated.

CONCLUSIONS

Zonisamide is well-tolerated and effective on the motor symptoms of myoclonus-dystonia.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that zonisamide improves myoclonus and related disability in patients with myoclonus-dystonia.

[Continuous subcutaneous infusion of apomorphine in Parkinson's disease: retrospective analysis of a series of 81 patients]

BACKGROUND

Continuous subcutaneous infusion of apomorphine (CAI) has shown efficacy in the treatment of motor fluctuations but its place in the therapeutic arsenal remains poorly defined in terms of indication, acceptability and long-term tolerance. Indeed, few studies have been carried out with a follow-up greater than 12 months. The main objective was to assess the quality of life of Parkinson's disease (PD) patients treated with CAI. We also evaluate the effectiveness on the motor fluctuations, the long-term tolerance of this treatment with its causes of discontinuation and the treatment regimens used.

METHODS

We conducted a retrospective study of 81 PD patients treated with CAI between April 2003 and June 2012. Data were collected from medical records. A repeated measures analysis of variance by the linear mixed model was used (significance level: 5%).

RESULTS

In August 2012, 27/81 patients were still treated with CAI with a mean duration of 28 months, 46/81 discontinued CAI (9 precociously), and 8 were lost to view. We didn't show improvement in the quality of life nor efficacy of CAI on the UPDRS IV score (P=0.54) and dyskinesia score (P=0.95). The CGI score patient also reflects this result with a majority response suggesting no significant change with CAI. We observed relative good cognitive and psychiatric tolerance. Adverse events were frequent but often benign. The average (±SD) rate of apomorphine was 3.15±1.71 mg/h and the oral dopaminergic treatment was decreased by 37.8%.

DISCUSSION

The results are consistent with the literature except for the lack of efficiency on motor fluctuations which may be due to the use of too small doses of apomorphine. This seems to be a leading cause of discontinuation of CAI, especially when it is associated with side effects or important constraints. For better efficiency on motor fluctuations, we recommend the use of apomorphine at higher doses to obtain an optimal continuous dopaminergic stimulation.

Protective effect of LRRK2 p.R1398H on risk of Parkinson's disease is independent of MAPT and SNCA variants

The best validated susceptibility variants for Parkinson's disease are located in the α-synuclein (SNCA) and microtubule-associated protein tau (MAPT) genes. Recently, a protective p.N551K-R1398H-K1423K haplotype in the leucine-rich repeat kinase 2 (LRRK2) gene was identified, with p.R1398H appearing to be the most likely functional variant. To date, the consistency of the protective effect of LRRK2 p.R1398H across MAPT and SNCA variant genotypes has not been assessed. To address this, we examined 4 SNCA variants (rs181489, rs356219, rs11931074, and rs2583988), the MAPT H1-haplotype-defining variant rs1052553, and LRRK2 p.R1398H (rs7133914) in Caucasian (n = 10,322) and Asian (n = 2289) series. There was no evidence of an interaction of LRRK2 p.R1398H with MAPT or SNCA variants (all p ≥ 0.10); the protective effect of p.R1398H was observed at similar magnitude across MAPT and SNCA genotypes, and the risk effects of MAPT and SNCA variants were observed consistently for LRRK2 p.R1398H genotypes. Our results indicate that the association of LRRK2 p.R1398H with Parkinson's disease is independent of SNCA and MAPT variants, and vice versa, in Caucasian and Asian populations.

Population-specific frequencies for LRRK2 susceptibility variants in the Genetic Epidemiology of Parkinson's Disease (GEO-PD) Consortium

BACKGROUND

Variants within the leucine-rich repeat kinase 2 gene are recognized as the most frequent genetic cause of Parkinson's disease. Leucine-rich repeat kinase 2 variation related to disease susceptibility displays many features that reflect the nature of complex, late-onset sporadic disorders like Parkinson's disease.

METHODS

The Genetic Epidemiology of Parkinson's Disease Consortium recently performed the largest genetic association study for variants in the leucine-rich repeat kinase 2 gene across 23 different sites in 15 countries.

RESULTS

Herein, we detail the allele frequencies for the novel risk factors (p.A419V and p.M1646T) and the protective haplotype (p.N551K-R1398H-K1423K) nominated in the original publication. Simple population allele frequencies not only can provide insight into the clinical relevance of specific variants but also can help genetically define patient groups.

CONCLUSIONS

Establishing individual patient-based genomic susceptibility profiles that incorporate both risk factors and protective factors will determine future diagnostic and treatment strategies.

Translation initiator EIF4G1 mutations in familial Parkinson disease

Genome-wide analysis of a multi-incident family with autosomal-dominant parkinsonism has implicated a locus on chromosomal region 3q26-q28. Linkage and disease segregation is explained by a missense mutation c.3614G>A (p.Arg1205His) in eukaryotic translation initiation factor 4-gamma (EIF4G1). Subsequent sequence and genotype analysis identified EIF4G1 c.1505C>T (p.Ala502Val), c.2056G>T (p.Gly686Cys), c.3490A>C (p.Ser1164Arg), c.3589C>T (p.Arg1197Trp) and c.3614G>A (p.Arg1205His) substitutions in affected subjects with familial parkinsonism and idiopathic Lewy body disease but not in control subjects. Despite different countries of origin, persons with EIF4G1 c.1505C>T (p.Ala502Val) or c.3614G>A (p.Arg1205His) mutations appear to share haplotypes consistent with ancestral founders. eIF4G1 p.Ala502Val and p.Arg1205His disrupt eIF4E or eIF3e binding, although the wild-type protein does not, and render mutant cells more vulnerable to reactive oxidative species. EIF4G1 mutations implicate mRNA translation initiation in familial parkinsonism and highlight a convergent pathway for monogenic, toxin and perhaps virally-induced Parkinson disease.

Independent and joint effects of the MAPT and SNCA genes in Parkinson disease

OBJECTIVE

We studied the independent and joint effects of the genes encoding alpha-synuclein (SNCA) and microtubule-associated protein tau (MAPT) in Parkinson disease (PD) as part of a large meta-analysis of individual data from case-control studies participating in the Genetic Epidemiology of Parkinson's Disease (GEO-PD) consortium.

METHODS

Participants of Caucasian ancestry were genotyped for a total of 4 SNCA (rs2583988, rs181489, rs356219, rs11931074) and 2 MAPT (rs1052553, rs242557) single nucleotide polymorphism (SNPs). Individual and joint effects of SNCA and MAPT SNPs were investigated using fixed- and random-effects logistic regression models. Interactions were studied on both a multiplicative and an additive scale, and using a case-control and case-only approach.

RESULTS

Fifteen GEO-PD sites contributed a total of 5,302 cases and 4,161 controls. All 4 SNCA SNPs and the MAPT H1-haplotype-defining SNP (rs1052553) displayed a highly significant marginal association with PD at the significance level adjusted for multiple comparisons. For SNCA, the strongest associations were observed for SNPs located at the 3' end of the gene. There was no evidence of statistical interaction between any of the 4 SNCA SNPs and rs1052553 or rs242557, neither on the multiplicative nor on the additive scale.

INTERPRETATION

This study confirms the association between PD and both SNCA SNPs and the H1 MAPT haplotype. It shows, based on a variety of approaches, that the joint action of variants in these 2 loci is consistent with independent effects of the genes without additional interacting effects.

SNCA locus duplication carriers: from genetics to Parkinson disease phenotypes

Genomic multiplication of the alpha-synuclein gene (SNCA) locus is one cause of familial Parkinson disease (PD). We performed detailed genomic, SNCA expression level, clinical, neuropsychological and functional imaging analyses of a parkinsonian kindred with a known duplication of the SNCA locus. We demonstrated that the duplication spanned 4.928 Mb (encompassing 31 known and putative genes) and was the largest to have been described at this locus. The presence of several repetitive long interspersed nuclear elements (LINEs) flanking the potential break area suggested that the duplication resulted from a genomic recombination between LINEs. We sequenced the break junction and confirmed the involvement of L1PA2 and L1PA4 in a non-allelic, homologous recombination. An analysis of mRNA levels in immortalized lymphoblastoid cells and peripheral blood mononuclear cells showed SNCA overexpression in subjects with the duplication, as well as overexpression of 13 other genes highlighting the usefulness of such cell models to study this duplication. Interestingly, abnormal tracer uptake in DaTSCAN(®) imaging correlated with the severity of the clinical symptoms. Our detailed genomic analysis and clinical exploration enabled us to specify the genotype-phenotype relationship, identify a case of presymptomatic PD and gain insight into the role of LINEs in SNCA locus duplication.

Transcriptional profile of Parkinson blood mononuclear cells with LRRK2 mutation

To gain insight into systemic molecular events associated with an age-related neurodegenerative disorder, we compared gene expression patterns in peripheral blood mononuclear cells (PBMCs) sampled from elderly, healthy controls and from Parkinson's disease (PD) patients carrying the most frequently found mutation of the LRRK2 gene (G2019S). A transcriptomic approach enabled us to detect differentially expressed genes and revealed perturbations of pathways known to be involved in PD-related neurodegeneration: the ubiquitin-proteasome system, the mitochondrial oxidation system, inflammation, axonal guidance, calcium signalling and apoptosis. Moreover, alterations of the MAP kinase pathway, the actin cytoskeleton, the ephrin receptor system and vesicular transport - all recently associated with the LRRK2 G2019S mutation pathogenesis - were noted. Furthermore, we acquired new evidences of dysregulation in leukocyte extravasation signalling and immune system pathways in PD. These data show that the G2019S mutation affects the entire body and highlight some of the molecular events observed in the brain. This PBMC transcriptomic approach could be used to better understand neurodegeneration in PD and decipher new pathogenetic mechanisms, even at early stages of the disease.

Crises temporales symptomatiques d’une intoxication au trichloroéthylène

INTRODUCTION

Trichloroethylene (TCE) is extensively used as a degreasing agent in the metal industry and as a solvent for organic compounds. Its neurotoxicity (with respect to both the peripheral and central nervous systems) is now widely acknowledged.

OBSERVATION

Here, we report the case of a 32-year-old male drug addict presenting temporal seizures after "huffing" TCE (i.e. voluntary inhalation). The patient also deve loped a "psycho-organic syndrome" which included cognitive dysfunction (with memory disorders in particular) and personality changes. These disorders had not been noticed by the patient's wife prior to the last episode of inhalation. Four months later, the cognitive disorders had stabilized and no further seizures had been observed.

CONCLUSION

The patient's overall clinical picture (notably featuring neuropsychological disorders) and electroencephalographic and brain imaging data argue in favor of a selective effect of TCE on the temporal lobe.