Ruth Djaldetti

VPS35 Mutations in Parkinson Disease

The identification of genetic causes for Mendelian disorders has been based on the collection of multi-incident families, linkage analysis, and sequencing of genes in candidate intervals. This study describes the application of next-generation sequencing technologies to a Swiss kindred presenting with autosomal-dominant, late-onset Parkinson disease (PD). The family has tremor-predominant dopa-responsive parkinsonism with a mean onset of 50.6 ± 7.3 years. Exome analysis suggests that an aspartic-acid-to-asparagine mutation within vacuolar protein sorting 35 (VPS35 c.1858G>A; p.Asp620Asn) is the genetic determinant of disease. VPS35 is a central component of the retromer cargo-recognition complex, is critical for endosome-trans-golgi trafficking and membrane-protein recycling, and is evolutionarily highly conserved. VPS35 c.1858G>A was found in all affected members of the Swiss kindred and in three more families and one patient with sporadic PD, but it was not observed in 3,309 controls. Further sequencing of familial affected probands revealed only one other missense variant, VPS35 c.946C>T; (p.Pro316Ser), in a pedigree with one unaffected and two affected carriers, and thus the pathogenicity of this mutation remains uncertain. Retromer-mediated sorting and transport is best characterized for acid hydrolase receptors. However, the complex has many types of cargo and is involved in a diverse array of biologic pathways from developmental Wnt signaling to lysosome biogenesis. Our study implicates disruption of VPS35 and retromer-mediated trans-membrane protein sorting, rescue, and recycling in the neurodegenerative process leading to PD.

Bax ablation prevents dopaminergic neurodegeneration in the 1-methyl- 4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) damages dopaminergic neurons in the substantia nigra pars compacta (SNpc) as seen in Parkinsons disease. Here, we show that the pro-apoptotic protein Bax is highly expressed in the SNpc and that its ablation attenuates SNpc developmental neuronal apoptosis. In adult mice, there is an up-regulation of Bax in the SNpc after MPTP administration and a decrease in Bcl-2. These changes parallel MPTP-induced dopaminergic neurodegeneration. We also show that mutant mice lacking Bax are significantly more resistant to MPTP than their wild-type littermates. This study demonstrates that Bax plays a critical role in the MPTP neurotoxic process and suggests that targeting Bax may provide protective benefit in the treatment of Parkinsons disease.

The natural history of multiple system atrophy: a prospective European cohort study

Summary Background Multiple system atrophy (MSA) is a fatal and still poorly understood degenerative movement disorder that is characterised by autonomic failure, cerebellar ataxia, and parkinsonism in various combinations. Here we present the final analysis of a prospective multicentre study by the European MSA Study Group to investigate the natural history of MSA. Methods Patients with a clinical diagnosis of MSA were recruited and followed up clinically for 2 years. Vital status was ascertained 2 years after study completion. Disease progression was assessed using the unified MSA rating scale (UMSARS), a disease-specific questionnaire that enables the semiquantitative rating of autonomic and motor impairment in patients with MSA. Additional rating methods were applied to grade global disease severity, autonomic symptoms, and quality of life. Survival was calculated using a Kaplan-Meier analysis and predictors were identified in a Cox regression model. Group differences were analysed by parametric tests and non-parametric tests as appropriate. Sample size estimates were calculated using a paired two-group t test. Findings 141 patients with moderately severe disease fulfilled the consensus criteria for MSA. Mean age at symptom onset was 56·2 (SD 8·4) years. Median survival from symptom onset as determined by Kaplan-Meier analysis was 9·8 years (95% CI 8·1–11·4). The parkinsonian variant of MSA (hazard ratio [HR] 2·08, 95% CI 1·09–3·97; p=0·026) and incomplete bladder emptying (HR 2·10, 1·02–4·30; p=0·044) predicted shorter survival. 24-month progression rates of UMSARS activities of daily living, motor examination, and total scores were 49% (9·4 [SD 5·9]), 74% (12·9 [8·5]), and 57% (21·9 [11·9]), respectively, relative to baseline scores. Autonomic symptom scores progressed throughout the follow-up. Shorter symptom duration at baseline (OR 0·68, 0·5–0·9; p=0·006) and absent levodopa response (OR 3·4, 1·1–10·2; p=0·03) predicted rapid UMSARS progression. Sample size estimation showed that an interventional trial with 258 patients (129 per group) would be able to detect a 30% effect size in 1-year UMSARS motor examination decline rates at 80% power. Interpretation Our prospective dataset provides new insights into the evolution of MSA based on a follow-up period that exceeds that of previous studies. It also represents a useful resource for patient counselling and planning of multicentre trials. Funding Fifth Framework Programme of the European Union, the Oesterreichische Nationalbank, and the Austrian Science Fund.

Camptocormia (bent spine) in patients with Parkinson's disease: Characterization and possible pathogenesis of an unusual phenomenon

Camptocormia is characterized by severe forward flexion of the thoracolumbar spine which increases while walking and disappears in the recumbent position. We describe for the first time eight patients with presumed idiopathic Parkinsons disease (mean age 66 ± 5 yrs; mean symptom duration 13.1 ± 5.1 yrs) who developed camptocormia. This impressive abnormal posture emerged 4–14 years from disease onset, and in some patients stooped posture was the prominent symptom at diagnosis. There was no clear correlation between camptocormia and levodopa treatment. In some patients the camptocormic posture improved, and in others it was unchanged or even aggravated following levodopa administration. Three patients reported worsening of this symptom during “off” periods and also with fatigue. The pathogenesis of this phenomenon is unknown but might represent either a rare type of dystonia or an extreme form of rigidity.

The mystery of motor asymmetry in Parkinson's disease

The motor symptoms of Parkinsons disease are predominantly due to progressive degeneration of nigral dopaminergic neurons. In most cases there is a substantial asymmetry of clinical symptoms from disease onset, which occurs in sporadic and in hereditary forms of the disease. However, the mechanism of such unilaterality of symptom appearance is not understood. There is only sparse information about whether symptom-side predominance is genetically coded and determined years before symptom onset, or whether it is acquired and related to side differences in vulnerability of the degenerating neurons. In this Personal View we review data for unilaterality of symptoms at different disease stages. We also discuss several pathological, genetic, environmental, and toxic possibilities for explaining the mechanism of side predominance.

Rasagiline mesylate, a new MAO-B inhibitor for the treatment of Parkinson's disease : A double-blind study as adjunctive therapy to levodopa

Rasagiline mesylate (TVP-1012) is a potent, selective, non-reversible MAO-B inhibitor, without the tyramine-potentiating effect and with neuroprotective activities. The benefit of rasagiline as monotherapy in patients with early Parkinsons disease (PD) has already been reported. To evaluate the safety, tolerability, and clinical effect of rasagiline as adjunctive therapy to levodopa, a multicenter, double-blind, randomized, placebo-controlled, parallel-group study (0.5, 1, and 2 mg/d) was conducted for 12 weeks in 70 patients with PD (mean age, 57.4 y; mean disease duration, 5.7 y; 32 patients had motor fluctuations). A beneficial clinical effect was observed in fluctuating patients treated with rasagiline (all doses), expressed as a decrease in total Unified Parkinsons Disease Rating Scale (UPDRS) score (23.0% vs 8.5% in the placebo group). The treatment effect was still evident 6 weeks after drug discontinuation (in all doses). The safety and tolerability of rasagiline were good. Adverse events were no different than those of patients taking placebo. Almost complete platelet MAO-B inhibition was obtained at all rasagiline doses. This study has demonstrated that rasagiline (up to 2 mg/day) has a good safety profile and a beneficial clinical effect in fluctuating patients with PD when given as an add-on to chronic levodopa therapy.

Presentation, diagnosis, and management of multiple system atrophy in Europe: Final analysis of the European multiple system atrophy registry†

Multiple system atrophy (MSA) is a Parkinsons Disease (PD)‐like α‐synucleinopathy clinically characterized by dysautonomia, parkinsonism, cerebellar ataxia, and pyramidal signs in any combination. We aimed to determine whether the clinical presentation of MSA as well as diagnostic and therapeutic strategies differ across Europe and Israel. In 19 European MSA Study Group centres all consecutive patients with a clinical diagnosis of MSA were recruited from 2001 to 2005. A standardized minimal data set was obtained from all patients. Four‐hundred thirty‐seven MSA patients from 19 centres in 10 countries were included. Mean age at onset was 57.8 years; mean disease duration at inclusion was 5.8 years. According to the consensus criteria 68% were classified as parkinsonian type (MSA‐P) and 32% as cerebellar type (MSA‐C) (probable MSA: 72%, possible MSA: 28%). Symptomatic dysautonomia was present in almost all patients, and urinary dysfunction (83%) more common than symptomatic orthostatic hypotension (75%). Cerebellar ataxia was present in 64%, and parkinsonism in 87%, of all cases. No significant differences in the clinical presentation were observed between the participating countries. In contrast, diagnostic work up and therapeutic strategies were heterogeneous. Less than a third of patients with documented orthostatic hypotension or neurogenic bladder disturbance were receiving treatment. This largest clinical series of MSA patients reported so far shows that the disease presents uniformly across Europe. The observed differences in diagnostic and therapeutic management including lack of therapy for dysautonomia emphasize the need for future guidelines in these areas.

[123I]-FP/CIT SPECT imaging for distinguishing drug-induced parkinsonism from Parkinson's disease

Parkinsonism in patients taking neuroleptic medications might be induced by dopamine receptor blockade alone or by dopamine blockade with nigrostriatal dysfunction. The differentiation between Parkinsons disease (PD) and drug‐induced parkinsonism (DIP) is difficult to assess on clinical grounds alone. In this study, we have evaluated the clinical characteristics and striatal binding of 123I‐FP‐CIT (N‐ω‐fluoropropyl‐2β‐carboxymethoxy‐3β‐{4‐iodophenyl}tropane) in patients who developed DIP. A total of 20 patients (mean age, 62 ± 13 years) who developed parkinsonism while on neuroleptic agents and 10 age‐matched controls were enrolled. [123]‐FP‐CIT single‐photon emission computed tomography (SPECT) was performed in all subjects. Neurological assessment was performed with the Motor part of the Unified Parkinsons Disease Rating Scale. [123]‐FP‐CIT binding of the entire striatum, caudate, and putamen was calculated. Patients were divided into two subgroups according to SPECT results for comparison of clinical characteristics. There were 9 patients who had normal scans and 11 who showed significantly diminished striatal binding, suggesting degeneration of the nigrostriatal system. Subanalyses of abnormal scans revealed significantly diminished binding in the caudate (P < 0.001 for right and left caudate) and putamen (P = 0.002 and P < 0.05 for right and left putamen, respectively). There were no differences in clinical features between patients with normal and abnormal scans. Symptoms included asymmetric tremor, bradykinesia, and rigidity in both groups. Freezing gait was present in two patients with normal scans. These results indicate that DIP is clinically indistinguishable from PD. Brain imaging with FP‐CIT helps to determine whether DIP is entirely drug‐induced or an exacerbation of subclinical PD.

Red Flags for Multiple System Atrophy

The clinical diagnosis of multiple system atrophy (MSA) is fraught with difficulty and there are no pathognomonic features to discriminate the parkinsonian variant (MSA‐P) from Parkinsons disease (PD). Besides the poor response to levodopa, and the additional presence of pyramidal or cerebellar signs (ataxia) or autonomic failure as major diagnostic criteria, certain other clinical features known as “red flags” or warning signs may raise the clinical suspicion of MSA. To study the diagnostic role of these features in MSA‐P versus PD patients, a standardized red flag check list (RFCL) developed by the European MSA Study Group (EMSA‐SG) was administered to 57 patients with probable MSA‐P and 116 patients with probable PD diagnosed according to established criteria. Those red flags with a specifity over 95% were selected for further analysis. Factor analysis was applied to reduce the number of red flags. The resulting set was then applied to 17 patients with possible MSA‐P who on follow‐up fulfilled criteria of probable MSA‐P. Red flags were grouped into related categories. With two or more of six red flag categories present specificity was 98.3% and sensitivity was 84.2% in our cohort. When applying these criteria to patients with possible MSA‐P, 76.5% of them would have been correctly diagnosed as probable MSA‐P 15.9 (±7.0) months earlier than with the Consensus criteria alone. We propose a combination of two out of six red flag categories as additional diagnostic criteria for probable MSA‐P.

IL-1β, IL-2, IL-6 and TNF-α production by peripheral blood mononuclear cells from patients with Parkinson's disease

Summary The capacity of peripheral blood mononuclear cells (PBMC) from patients with treated Parkinsons disease (PD) to produce interleukin (IL) IL-1β IL-2, IL-6, tumor necrosis factor (TNF)-α and the proliferative response to mitogens, was compared with that from cells from healthy subjects. The production of IL-2 and the mitogen response were significantly lower in PD patients, whereas the secretion of IL-1β, IL-6 and TNF-α were significantly enhanced. To evaluate the role of levodopa in creating immunological alterations, PBMC of patients and controls were incubated with concentrations of the drug extrapolated from those used in clinical practice. Levodopa caused an inhibition of mitogen-induced proliferation, stimulation of IL-6 and TNF-α production, whereas the secretion of IL-1β and IL-2 was not affected. The results of the study provide a further support for the interrelationship between the central nervous and immune system. In addition, the data indicate that the immunological alterations found in PD may be partially attributed to levodopa administration.