Christoph Kamm

GLUT1 mutations are a cause of paroxysmal exertion-induced dyskinesias and induce hemolytic anemia by a cation leak

Paroxysmal dyskinesias are episodic movement disorders that can be inherited or are sporadic in nature. The pathophysiology underlying these disorders remains largely unknown but may involve disrupted ion homeostasis due to defects in cell-surface channels or nutrient transporters. In this study, we describe a family with paroxysmal exertion-induced dyskinesia (PED) over 3 generations. Their PED was accompanied by epilepsy, mild developmental delay, reduced CSF glucose levels, hemolytic anemia with echinocytosis, and altered erythrocyte ion concentrations. Using a candidate gene approach, we identified a causative deletion of 4 highly conserved amino acids (Q282_S285del) in the pore region of the glucose transporter 1 (GLUT1). Functional studies in Xenopus oocytes and human erythrocytes revealed that this mutation decreased glucose transport and caused a cation leak that alters intracellular concentrations of sodium, potassium, and calcium. We screened 4 additional families, in which PED is combined with epilepsy, developmental delay, or migraine, but not with hemolysis or echinocytosis, and identified 2 additional GLUT1 mutations (A275T, G314S) that decreased glucose transport but did not affect cation permeability. Combining these data with brain imaging studies, we propose that the dyskinesias result from an exertion-induced energy deficit that may cause episodic dysfunction of the basal ganglia, and that the hemolysis with echinocytosis may result from alterations in intracellular electrolytes caused by a cation leak through mutant GLUT1.

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.

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.

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.

Minocycline 1‐year therapy in multiple‐system‐atrophy: Effect on clinical symptoms and [11C] (R)‐PK11195 PET (MEMSA‐trial)

The aim of the study was to investigate the efficacy of the antibiotic minocycline as a drug treatment in patients with Multiple‐System‐Atrophy Parkinson‐type (MSA‐P). Sixty‐three patients were randomized to minocycline 200 mg/d (n = 32) or a matching placebo (n = 31). The primary outcome variable was the change in the value of the motor score of the Unified Multiple‐System‐Atrophy Rating‐Scale (UMSARSII) from baseline to 48 weeks. Secondary outcome variables included subscores and individual Parkinsonian symptoms as determined by the UMSARS and the Unified‐Parkinsons‐Disease Rating‐Scale (UPDRS). Health‐related quality of life (HrQoL) was assessed using the EQ‐5D and SF‐12. “Progression rate” was assumed to be reflected in the change in motor function over 48 weeks. At 24 weeks and 48 weeks of follow‐up, there was a significant deterioration in motor scores in both groups, but neither the change in UMSARSII nor in UPDRSIII differed significantly between treatment groups, i.e. “progression rate” was considered to be similar in both treatment arms. HrQoL did not differ among the two treatment arms. In a small subgroup of patients (n = 8; minocycline = 3, placebo = 5)[11C](R)‐PK11195‐PET was performed. The three patients in the minocycline group had an attenuated mean increase in microglial activation as compared to the placebo group (P = 0.07) and in two of them individually showed decreased [11C](R)‐PK11195 binding actually decreased. These preliminary PET‐data suggest that minocycline may interfere with microglial activation. The relevance of this observation requires further investigation. This prospective, 48 week, randomized, double‐blind, multinational study failed to show a clinical effect of minocycline on symptom severity as assessed by clinical motor function.

Progression of multiple system atrophy (MSA): A prospective natural history study by the European MSA study group (EMSA SG)

The disease‐specific Unified Multiple System Atrophy Rating Scale (UMSARS) has been developed recently and validated for assessing disease severity in multiple system atrophy (MSA). Here, we aimed at (1) assessing rates of disease progression in MSA and (2) validating UMSARS for sensitivity to change over time. Impairment was assessed at two time points 12 months apart using UMSARS Part I (historical review), UMSARS Part II (motor examination), as well as measures of global disease severity, including UMSARS Part IV, Hoehn and Yahr (HY) Parkinsons disease staging, Schwab England Activities of Daily Living (SE ADL), and a three‐point global Severity Scale (SS3). Fifty patients (male:female ratio, 1:0.9; possible MSA, 16%; probable MSA, 84%; MSA‐parkinsonian, 58%; MSA‐cerebellar, 42%) were assessed twice with an interval of 12.3 months. UMSARS II scores progressed by 57.3% (P < 0.0001) and UMSARS I scores by 35.6% (P < 0.0001) in relation to the respective baseline scores with no differences between motor subtypes, diagnostic categories and gender. Significant inverse correlations between (1) UMSARS I or UMSARS II progression and (2) baseline disability measures (i.e., the respective UMSARS or SS3 scores) and disease duration were found. Furthermore, the increases in HY staging, SE ADL and SS3 correlated significantly with UMSARS I, UMSARS II, and UMSARS IV progression. This report is the first prospective study showing rapid annual UMSARS rates of decline in MSA. Our data contribute to the ongoing validation process of UMSARS, and they facilitate the planning and implementation of future neuroprotective intervention trials.

Paroxysmal choreoathetosis/spasticity (DYT9) is caused by a GLUT1 defect

Objective: Mutations in SLC2A1, encoding the glucose transporter type 1 (GLUT1), cause a broad spectrum of neurologic disorders including classic GLUT1 deficiency syndrome, paroxysmal exercise-induced dyskinesia (PED, DYT18), and absence epilepsy. A large German/Dutch pedigree has formerly been described as paroxysmal choreoathetosis/spasticity (DYT9) and linked close to but not including the SLC2A1 locus on chromosome 1p. We tested whether 1) progressive spastic paraparesis, in addition to PED, as described in DYT9, and 2) autosomal dominant forms of hereditary spastic paraparesis (HSP) without PED are caused by SLC2A1 defects. Methods: The German/Dutch family and an Australian monozygotic twin pair were clinically (re-)investigated, and 139 index cases with dominant or sporadic HSP in which relevant dominant genes were partially excluded were identified from databanks. SLC2A1 was sequenced in all cases in this observational study and the functional effects of identified sequence variations were tested in glucose uptake and protein expression assays. Results: We identified causative mutations in SLC2A1 in both families, which were absent in 400 control chromosomes, cosegregated with the affection status, and decreased glucose uptake in functional assays. In the 139 index patients with HSP without paroxysmal dyskinesias, we only identified one sequence variation, which, however, neither decreased glucose uptake nor altered protein expression. Conclusions: This study shows that DYT9 and DYT18 are allelic disorders and enlarges the spectrum of GLUT1 phenotypes, now also including slowly progressive spastic paraparesis combined with PED. SLC2A1 mutations were excluded as a cause of HSP without PED in our cohort.

The European Multiple System Atrophy-Study Group (EMSA-SG)

Summary.Introduction. The European Multiple System Atrophy-Study Group (EMSA-SG) is an academic network comprising 23 centers across Europe and Israel that has constituted itself already in January 1999. This international forum of established experts under the guidance of the University Hospital of Innsbruck as coordinating center is supported by the 5th framework program of the European Union since March 2001 (QLK6-CT-2000-00661). Objectives. Primary goals of the network include (1) a central Registry for European multiple system atrophy (MSA) patients, (2) a decentralized DNA Bank, (3) the development and validation of the novel Unified MSA Rating Scale (UMSARS), (4) the conduction of a Natural History Study (NHS), and (5) the planning or implementation of interventional therapeutic trials. Methods. The EMSA-SG Registry is a computerized data bank localized at the coordinating centre in Innsbruck collecting diagnostic and therapeutic data of MSA patients. Blood samples of patients and controls are recruited into the DNA Bank. The UMSARS is a novel specific rating instrument that has been developed and validated by the EMSA-SG. The NHS comprises assessments of basic anthropometric data as well as a range of scales including the UMSARS, Unified Parkinson’s Disease Rating Scale (UPDRS), measures of global disability, Red Flag list, MMSE (Mini Mental State Examination), quality of live measures, i.e. EuroQoL 5D (EQ-5D) and Medical Outcome Study Short Form (SF-36) as well as the Beck Depression Inventory (BDI). In a subgroup of patients dysautonomic features are recorded in detail using the Queen Square Cardiovascular Autonomic Function Test Battery, the Composite Autonomic Symptom Scale (COMPASS) and measurements of residual urinary volume. Most of these measures are repeated at 6-monthly follow up visits for a total study period of 24 months. Surrogate markers of the disease progression are identified by the EMSA-SG using magnetic resonance and diffusion weighted imaging (MRI and DWI, respectively). Results. 412 patients have been recruited into the Registry so far. Probable MSA-P was the most common diagnosis (49% of cases). 507 patients donated DNA for research. 131 patients have been recruited into the NHS. There was a rapid deterioration of the motor disorder (in particular akinesia) by 26.1% of the UMSARS II, and – to a lesser degree – of activities of daily living by 16.8% of the UMSARS I in relation to the respective baseline scores. Motor progression was associated with low motor or global disability as well as low akinesia or cerebellar subscores at baseline. Mental function did not deteriorate during this short follow up period. Conclusion. For the first time, prospective data concerning disease progression are available. Such data about the natural history and prognosis of MSA as well as surrogate markers of disease process allow planning and implementation of multi-centre phase II/III neuroprotective intervention trials within the next years more effectively. Indeed, a trial on growth hormone in MSA has just been completed, and another on minocycline will be completed by the end of this year.

Short- and long-term outcome of chronic pallidal neurostimulation in monogenic isolated dystonia

Objectives: Deep brain stimulation of the internal pallidum (GPi-DBS) is an established therapeutic option in treatment-refractory dystonia, and the identification of factors predicting surgical outcome is needed to optimize patient selection. Methods: In this retrospective multicenter study, GPi-DBS outcome of 8 patients with DYT6, 9 with DYT1, and 38 with isolated dystonia without known monogenic cause (non-DYT) was assessed at early (1–16 months) and late (22–92 months) follow-up using Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores. Results: At early follow-up, mean reduction of dystonia severity was greater in patients with DYT1 (BFMDRS score: −60%) and non-DYT dystonia (−52%) than in patients with DYT6 dystonia (−32%; p = 0.046). Accordingly, the rate of responders was considerably lower in the latter group (57% vs >90%; p = 0.017). At late follow-up, however, GPi-DBS resulted in comparable improvement in all 3 groups (DYT6, −42%; DYT1, −44; non-DYT, −61%). Additional DBS of the same or another brain target was performed in 3 of 8 patients with DYT6 dystonia with varying results. Regardless of the genotype, patients with a shorter duration from onset of dystonia to surgery had better control of dystonia postoperatively. Conclusions: Long-term GPi-DBS is effective in patients with DYT6, DYT1, and non-DYT dystonia. However, the effect of DBS appears to be less predictable in patients with DYT6, suggesting that pre-DBS genetic testing and counseling for known dystonia gene mutations may be indicated. GPi-DBS should probably be considered earlier in the disease course. Classification of evidence: This study provides Class IV evidence that long-term GPi-DBS improves dystonia in patients with DYT1, DYT6, and non-DYT dystonia.

A functional polymorphism regulating dopamine beta-hydroxylase influences against Parkinson's disease.

A functional −1021C → T polymorphism in the dopamine β‐hydroxylase gene has been demonstrated to regulate plasma DBH activity. We report that individuals with genetically determined low serum DBH activity (genotype T/T) have protection against Parkinsons disease (p = 0.01). In particular, we observed an underrepresentation of the T/T genotype odds ratio = 0.46 (CI = 0.27‐0.8). Rather than identifying a haplotype, or a marker in linkage disequilibrium with the risk variant, this to our knowledge is the first report directly linking PD susceptibility with a proven functional variant. Ann Neurol 2004