P14.102 Cerebellar atrophy patterns in paraneoplastic cerebellar degeneraiton and spinocerebellar ataxia 1 (SCA1)

BACKGROUND

Brain and more specifically cerebellar atrophy is a major radiological finding in both Paraneoplastic Cerebellar Degeneration (PCD) with anti-Yo antibodies and Spinocerebellar Ataxia type 1 (SCA1).We sought to analyze the different brain volumetric patterns of cerebellar atrophy in these diseases.

MATERIAL AND METHODS

We performed a retrospective multicentric study (Paris, Lyon, Barcelona reference centres) with either anti-Yo PCD (n=16) or SCA1 (n=17) and 30 healthy subjects paired by age. We used VolBrain and CERES algorithms to obtain the brain and cerebellum segmentation, respectively as well as the cortical thickness. We used a Sparse Canonical Correlation Analysis (SCCAN) and Voxel Brain Morphometry (VBM) with family wise error correction to analyze volumetric differences between the different conditions.

RESULTS

SCA patients were younger than PCD patients (p<0.05, ANOVA). In univariate analysis, most of the atrophic regions (p<0.05) were common between PCD and SCA1 compared to controls. Isolated cortical thickness and grey matter analysis showed predominant atrophy in PCD patients. Multivariate analysis using SCCAN and VBM confirmed these results. We identified a particular atrophy pattern in PCD patients involving lobules III to VII. We observed a more diffuse atrophy distribution in SCA1 patients and a lower cortical atrophy in PCD patients.

CONCLUSION

We described the specific pattern of topographic cerebellar atrophy in PCD and SCA1 patients. The cerebellar atrophy in PCD is mainly localized in the neocerebellum.

The neuroanatomy of subthreshold depressive symptoms in Huntington's disease: a combined diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) study

BACKGROUND

Depressive symptoms are prominent psychopathological features of Huntington's disease (HD), making a negative impact on social functioning and well-being.

METHOD

We compared the frequencies of a history of depression, previous suicide attempts and current subthreshold depression between 61 early-stage HD participants and 40 matched controls. The HD group was then split based on the overall HD group's median Hospital Anxiety and Depression Scale-depression score into a group of 30 non-depressed participants (mean 0.8, s.d. = 0.7) and a group of 31 participants with subthreshold depressive symptoms (mean 7.3, s.d. = 3.5) to explore the neuroanatomy underlying subthreshold depressive symptoms in HD using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI).

RESULTS

Frequencies of history of depression, previous suicide attempts or current subthreshold depressive symptoms were higher in HD than in controls. The severity of current depressive symptoms was also higher in HD, but not associated with the severity of HD motor signs or disease burden. Compared with the non-depressed HD group DTI revealed lower fractional anisotropy (FA) values in the frontal cortex, anterior cingulate cortex, insula and cerebellum of the HD group with subthreshold depressive symptoms. In contrast, VBM measures were similar in both HD groups. A history of depression, the severity of HD motor signs or disease burden did not correlate with FA values of these regions.

CONCLUSIONS

Current subthreshold depressive symptoms in early HD are associated with microstructural changes - without concomitant brain volume loss - in brain regions known to be involved in major depressive disorder, but not those typically associated with HD pathology.

EFNS/ENS Consensus on the diagnosis and management of chronic ataxias in adulthood

BACKGROUND AND OBJECTIVES

The ataxias are a challenging group of neurological diseases due the aetiological heterogeneity and the complexity of the genetic subtypes. This guideline focuses on the heredodegenerative ataxias. The aim is to provide a peer-reviewed evidence-based guideline for clinical neurologists and other specialist physicians responsible for the care of patients with ataxia.

METHODS

This guideline is based on systematic evaluations of the relevant literature and on three consensus meetings of the task force.

DIAGNOSIS

If acquired causes are ruled out, and if the disease course is rather slowly progressive, a (heredo)degenerative disease is likely. A positive family history gives much guidance. In the case of a dominant family history, first line genetic screening is recommended for spinocerebellar ataxia (SCA) 1, 2, 3, 6, 7 and 17 (level B), and in Asian patients also for dentatorubral-pallidoluysian atrophy (DRPLA). In the case of recessive disease, a stepwise diagnostic work-up is recommended, including both biochemical markers and targeted genetic testing, particularly aimed at Friedreich's ataxia, ataxia telangiectasia, ataxia due to vitamin E deficiency, polymerase gamma gene (POLG gene, various mutations), autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) and ataxia with oculomotor apraxia (AOA) types 1 and 2. If family history is negative, we still advise to screen for the more common dominant and recessive ataxias. In addition, if onset is below 45 years we recommend the full work-up for recessive ataxias; if onset is above 45 years we recommend to screen for fragile X mental retardation 1 FMR1 premutations (good practice points). In sporadic cases with an onset after 30 years, a diagnosis of multiple system atrophy should be considered (good practice point). In particular the genetic work-up will change over the upcoming years due to the diagnostic utility of new techniques such as gene panel diagnostics based on next generation sequencing for routine work-up, or even whole exome and genome sequencing for selected cases.

TREATMENT

Some of the rare recessive ataxias are treatable, but for most of the heredodegenerative ataxias treatment is purely symptomatic. Idebenone is not effective in Friedreich's ataxia (level A). Riluzole (level B) and amantadine (level C) might provide symptomatic relief, irrespective of exact etiology. Also, varenicline for SCA3 patients (level B) can be considered. There is level Class II evidence to recommend physiotherapy, and Class III data to support occupational therapy.

Novel SPG10 mutation associated with dysautonomia, spinal cord atrophy, and skin biopsy abnormality

BACKGROUND

SPG10 is a rare form of autosomic dominant hereditary spastic paraplegia (HSP) caused by mutations in the KIF5A gene, which may be involved in axonal transport.

METHODS

We report the characteristics of a French family with a novel missense mutation c.580 G>C in exon 7 of the KIF5A gene.

RESULTS

The proband and his sister presented with an adult onset HSP, a sensory spinal cord-like syndrome, dysautonomia, and severe axonal polyneuropathy. Contrary to the proband, his sister presented a secondary improvement in spasticity and walking. In the proband, MRI findings consisted in spinal cord atrophy and symmetric cerebral demyelination, whereas the skin biopsy suggested a defect in the number of vesicles and synaptophysin density at the pre-synaptic membrane.

CONCLUSION

This study extends the phenotype of SPG10 and argues for abnormalities in the axonal vesicular transport.

The natural history of spinocerebellar ataxia type 1, 2, 3, and 6: a 2-year follow-up study

OBJECTIVE

To obtain quantitative data on the progression of the most common spinocerebellar ataxias (SCAs) and identify factors that influence their progression, we initiated the EUROSCA natural history study, a multicentric longitudinal cohort study of 526 patients with SCA1, SCA2, SCA3, or SCA6. We report the results of the 1- and 2-year follow-up visits.

METHODS

As the primary outcome measure we used the Scale for the Assessment and Rating of Ataxia (SARA, 0-40), and as a secondary measure the Inventory of Non-Ataxia Symptoms (INAS, 0-16) count.

RESULTS

The annual increase of the SARA score was greatest in SCA1 (2.18 ± 0.17, mean ± SE) followed by SCA3 (1.61 ± 0.12) and SCA2 (1.40 ± 0.11). SARA progression in SCA6 was slowest and nonlinear (first year: 0.35 ± 0.34, second year: 1.44 ± 0.34). Analysis of the INAS count yielded similar results. Larger expanded repeats and earlier age at onset were associated with faster SARA progression in SCA1 and SCA2. In SCA1, repeat length of the expanded allele had a similar effect on INAS progression. In SCA3, SARA progression was influenced by the disease duration at inclusion, and INAS progression was faster in females.

CONCLUSIONS

Our study gives a comprehensive quantitative account of disease progression in SCA1, SCA2, SCA3, and SCA6 and identifies factors that specifically affect disease progression.

Autosomal dominant cerebellar ataxias

Cerebellar ataxias with autosomal dominant transmission (ADCA) are far rarer than sporadic cases of cerebellar ataxia. The identification of genes involved in dominant forms has confirmed the genetic heterogeneity of these conditions and of the underlying mechanisms and pathways. To date, at least 28 genetic loci and, among them, 20 genes have been identified. In many instances, the phenotype is not restricted to cerebellar dysfunction but includes more complex multisystemic neurological deficits. Seven ADCA (SCA1, 2, 3, 6, 7, 17, and dentatorubro-pallido-luysian atrophy) are caused by repeat expansions in the corresponding proteins; phenotype-genotype correlations have shown that repeat size influences the progression of the disease, its severity and clinical differences among patients, including the phenomenon of anticipation between generations. All other ADCA are caused either by non-coding repeat expansions, conventional mutations or large rearrangements in genes with different functions. This review will focus on the genetic features of ADCA and on the clinical differences among the different forms.

[Genetic testing in asymptomatic minors: a survey among French geneticists]

Since their introduction, genetic tests have been carefully considered, with special attention to the release of information about the test and test results, the confidentiality of genetic information, the request and its motivation, and the psychological impact of the test. Careful consideration is needed when family members at risk are asymptomatic children or adolescents. Cautious reflection is warranted on whether and under which conditions genetic testing should be performed. Here, we report on the results of a survey conducted in France among 50 geneticists questioned on their opinions and practices concerning presymptomatic testing in three groups of diseases: those for which a medical benefit exists during childhood (e.g., retinoblastoma), diseases with onset during childhood for which there are no immediate medical consequences (e.g., type II/III spinal muscular atrophy), and those with onset during adulthood for which there is no medical benefit during childhood (e.g., Huntington disease). Guidelines are proposed: presymptomatic testing should not be performed in a minor without individual and direct information, all requests for presymptomatic genetic testing concerning a disease with onset in adulthood should be postponed, and all presymptomatic test requests for a minor should be addressed to a multidisciplinary team.

Multicenter analysis of glucocerebrosidase mutations in Parkinson's disease

BACKGROUND

Recent studies indicate an increased frequency of mutations in the gene encoding glucocerebrosidase (GBA), a deficiency of which causes Gaucher's disease, among patients with Parkinson's disease. We aimed to ascertain the frequency of GBA mutations in an ethnically diverse group of patients with Parkinson's disease.

METHODS

Sixteen centers participated in our international, collaborative study: five from the Americas, six from Europe, two from Israel, and three from Asia. Each center genotyped a standard DNA panel to permit comparison of the genotyping results across centers. Genotypes and phenotypic data from a total of 5691 patients with Parkinson's disease (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews) were analyzed, with multivariate logistic-regression models and the Mantel-Haenszel procedure used to estimate odds ratios across centers.

RESULTS

All 16 centers could detect two GBA mutations, L444P and N370S. Among Ashkenazi Jewish subjects, either mutation was found in 15% of patients and 3% of controls, and among non-Ashkenazi Jewish subjects, either mutation was found in 3% of patients and less than 1% of controls. GBA was fully sequenced for 1883 non-Ashkenazi Jewish patients, and mutations were identified in 7%, showing that limited mutation screening can miss half the mutant alleles. The odds ratio for any GBA mutation in patients versus controls was 5.43 across centers. As compared with patients who did not carry a GBA mutation, those with a GBA mutation presented earlier with the disease, were more likely to have affected relatives, and were more likely to have atypical clinical manifestations.

CONCLUSIONS

Data collected from 16 centers demonstrate that there is a strong association between GBA mutations and Parkinson's disease.

Molecular analyses of the LRRK2 gene in European and North African autosomal dominant Parkinson's disease

BACKGROUND

Mutations in the leucine-rich-repeat kinase 2 (LRRK2) gene have been identified in families with autosomal dominant Parkinson's disease (ADPD), the most common of which is the p.G2019S substitution that has been found at varying frequencies worldwide. Because of the size of the LRRK2 gene, few studies have analysed the entire gene in large series of ADPD families.

METHODS

We performed extensive mutation analyses of all 51 coding exons of the LRRK2 gene in index cases from 226 Parkinson's disease families compatible with autosomal dominant inheritance, mostly from France (n = 182) and North Africa (n = 14).

RESULTS

We found 79 sequence variants, 29 of which were novel. Eight potentially or proven pathogenic mutations were found in 22 probands (9.7%). There were four novel amino acid substitutions that are potentially pathogenic (p.S52F, p.N363S, p.I810V, p.R1325Q) and two novel variants, p.H1216R and p.T1410M, that are probably not causative. The common p.G2019S mutation was identified in 13 probands (5.8%) including six from North Africa (43%). The known heterozygous p.R1441H and p.I1371V mutations were found in two probands each, and the p.E334K variant was identified in one single patient. Most potentially or proven pathogenic mutations were located in the functional domains of the Lrrk2 protein.

CONCLUSION

This study leads us to conclude that LRRK2 mutations are a common cause of autosomal dominant Parkinson's disease in Europe and North Africa.

Autosomal dominant spastic paraplegia with peripheral neuropathy maps to chr12q23-24

OBJECTIVE

Hereditary spastic paraplegias (HSP) are genetically exceedingly heterogeneous. To date, 37 genetic loci for HSP have been described (SPG1-41), among them 16 loci for autosomal dominant disease. Notwithstanding, further genetic heterogeneity is to be expected in HSP, as various HSP families do not link to any of the known HSP loci. In this study, we aimed to map the disease locus in a German family segregating autosomal dominant complicated HSP.

METHODS

A genome-wide linkage analysis was performed using the GeneChip Mapping 10Kv2.0 Xba Array containing 10,204 SNP markers. Suggestive loci were further analyzed by mapping of microsatellite markers.

RESULTS

One locus on chromosome 12q23-24, termed SPG36, was confirmed by high density microsatellite fine mapping with a significant LOD score of 3.2. SPG36 is flanked by markers D12S318 and D12S79. Linkage to SPG36 was excluded in >20 additional autosomal dominant HSP families. Candidate genes were selected and sequenced. No disease-causing mutations were identified in the coding regions of ATXN2, HSPB8, IFT81, Myo1H, UBE3B, and VPS29. SPG36 is complicated by a sensory and motor neuropathy; it is therefore the eighth autosomal dominant subtype of complicated HSP.

CONCLUSION

We report mapping of a new locus for autosomal dominant hereditary spastic paraplegia (HSP) (SPG36) on chromosome 12q23-24 in a German family with autosomal dominant HSP complicated by peripheral neuropathy.

Striatal degeneration impairs language learning: evidence from Huntington's disease

Although the role of the striatum in language processing is still largely unclear, a number of recent proposals have outlined its specific contribution. Different studies report evidence converging to a picture where the striatum may be involved in those aspects of rule-application requiring non-automatized behaviour. This is the main characteristic of the earliest phases of language acquisition that require the online detection of distant dependencies and the creation of syntactic categories by means of rule learning. Learning of sequences and categorization processes in non-language domains has been known to require striatal recruitment. Thus, we hypothesized that the striatum should play a prominent role in the extraction of rules in learning a language. We studied 13 pre-symptomatic gene-carriers and 22 early stage patients of Huntington's disease (pre-HD), both characterized by a progressive degeneration of the striatum and 21 late stage patients Huntington's disease (18 stage II, two stage III and one stage IV) where cortical degeneration accompanies striatal degeneration. When presented with a simplified artificial language where words and rules could be extracted, early stage Huntington's disease patients (stage I) were impaired in the learning test, demonstrating a greater impairment in rule than word learning compared to the 20 age- and education-matched controls. Huntington's disease patients at later stages were impaired both on word and rule learning. While spared in their overall performance, gene-carriers having learned a set of abstract artificial language rules were then impaired in the transfer of those rules to similar artificial language structures. The correlation analyses among several neuropsychological tests assessing executive function showed that rule learning correlated with tests requiring working memory and attentional control, while word learning correlated with a test involving episodic memory. These learning impairments significantly correlated with the bicaudate ratio. The overall results support striatal involvement in rule extraction from speech and suggest that language acquisition requires several aspects of memory and executive functions for word and rule learning.

Second consensus statement on the diagnosis of multiple system atrophy

BACKGROUND

A consensus conference on multiple system atrophy (MSA) in 1998 established criteria for diagnosis that have been accepted widely. Since then, clinical, laboratory, neuropathologic, and imaging studies have advanced the field, requiring a fresh evaluation of diagnostic criteria. We held a second consensus conference in 2007 and present the results here.

METHODS

Experts in the clinical, neuropathologic, and imaging aspects of MSA were invited to participate in a 2-day consensus conference. Participants were divided into five groups, consisting of specialists in the parkinsonian, cerebellar, autonomic, neuropathologic, and imaging aspects of the disorder. Each group independently wrote diagnostic criteria for its area of expertise in advance of the meeting. These criteria were discussed and reconciled during the meeting using consensus methodology.

RESULTS

The new criteria retain the diagnostic categories of MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia to designate the predominant motor features and also retain the designations of definite, probable, and possible MSA. Definite MSA requires neuropathologic demonstration of CNS alpha-synuclein-positive glial cytoplasmic inclusions with neurodegenerative changes in striatonigral or olivopontocerebellar structures. Probable MSA requires a sporadic, progressive adult-onset disorder including rigorously defined autonomic failure and poorly levodopa-responsive parkinsonism or cerebellar ataxia. Possible MSA requires a sporadic, progressive adult-onset disease including parkinsonism or cerebellar ataxia and at least one feature suggesting autonomic dysfunction plus one other feature that may be a clinical or a neuroimaging abnormality.

CONCLUSIONS

These new criteria have simplified the previous criteria, have incorporated current knowledge, and are expected to enhance future assessments of the disease.

Spinocerebellar ataxia types 1, 2, 3, and 6: disease severity and nonataxia symptoms

OBJECTIVE

To identify factors that determine disease severity and clinical phenotype of the most common spinocerebellar ataxias (SCAs), we studied 526 patients with SCA1, SCA2, SCA3. or SCA6.

METHODS

To measure the severity of ataxia we used the Scale for the Assessment and Rating of Ataxia (SARA). In addition, nonataxia symptoms were assessed with the Inventory of Non-Ataxia Symptoms (INAS). The INAS count denotes the number of nonataxia symptoms in each patient.

RESULTS

An analysis of covariance with SARA score as dependent variable and repeat lengths of the expanded and normal allele, age at onset, and disease duration as independent variables led to multivariate models that explained 60.4% of the SARA score variance in SCA1, 45.4% in SCA2, 46.8% in SCA3, and 33.7% in SCA6. In SCA1, SCA2, and SCA3, SARA was mainly determined by repeat length of the expanded allele, age at onset, and disease duration. The only factors determining the SARA score in SCA6 were age at onset and disease duration. The INAS count was 5.0 +/- 2.3 in SCA1, 4.6 +/- 2.2 in SCA2, 5.2 +/- 2.5 in SCA3, and 2.0 +/- 1.7 in SCA6. In SCA1, SCA2, and SCA3, SARA score and disease duration were the strongest predictors of the INAS count. In SCA6, only age at onset and disease duration had an effect on the INAS count.

CONCLUSIONS

Our study suggests that spinocerebellar ataxia (SCA) 1, SCA2, and SCA3 share a number of common biologic properties, whereas SCA6 is distinct in that its phenotype is more determined by age than by disease-related factors.

Myoclonus-dystonia: clinical and electrophysiologic pattern related to SGCE mutations

OBJECTIVE

To clarify the clinical and neurophysiologic spectrum of myoclonus-dystonia patients with mutations of the SGCE gene.

METHODS

We prospectively studied 41 consecutive patients from 22 families with documented mutations of the SGCE gene. The patients had a standardized interview, neurologic examination, and detailed neurophysiologic examination, including surface polymyography, long-loop C-reflex studies, and EEG jerk-locked back averaging.

RESULTS

We noted a homogeneous electrophysiologic pattern of myoclonus of subcortical origin with short jerks (mean 95 msec, range 25 to 256 msec) at rest, during action, and during posture; there were no features of cortical hyperexcitability (specifically no abnormal C-reflex response and no short-latency premyoclonic potential on back-averaging studies). Myoclonus was either isolated or associated with mild to moderate dystonia, and predominated in the neck/trunk or proximal upper limbs in most cases. We found that 22% of the patients had a spontaneous improvement in their dystonia before reaching adulthood and that hypotonia can occasionally be a presenting symptom of the disorder.

CONCLUSION

We describe the myoclonus in patients with mutations in the SGCE gene and characterize the electrophysiologic pattern of this myoclonus. This pattern may help to improve the sensitivity of molecular tests and to define homogeneous populations suitable for inclusion in therapeutic trials.

Decreased expression of the mitochondrial matrix proteases Lon and ClpP in cells from a patient with hereditary spastic paraplegia (SPG13)

The mitochondrial chaperonin heat shock protein 60 (Hsp60) assists the folding of a subset of proteins localized in mitochondria and is an essential component of the mitochondrial protein quality control system. Mutations in the HSPD1 gene that encodes Hsp60 have been identified in patients with an autosomal dominant form of hereditary spastic paraplegia (SPG13), a late-onset neurodegenerative disorder characterized by a progressive paraparesis of the lower limbs. The disease-associated Hsp60-(p.Val98Ile) protein, encoded by the c.292G>A HSPD1 allele, has reduced chaperonin activity, but how its expression affects mitochondrial functions has not been investigated. We have studied mitochondrial function and expression of genes encoding mitochondrial chaperones and proteases in a human lymphoblastoid cell line and fibroblast cells from a patient who is heterozygous for the c.292G>A HSPD1 allele. We found that both the c.292G>A RNA transcript and the corresponding Hsp60-(p.Val98Ile) protein were present at comparable levels to their wild-type counterparts in SPG13 patient cells. Compared with control cells, we found no significant cellular or mitochondrial dysfunctions in SPG13 patient cells by assessing the mitochondrial membrane potential, cell viability, and sensitivity toward oxidative stress. However, a decreased expression of the mitochondrial protein quality control proteases Lon and ClpP, both at the RNA and protein level, was demonstrated in SPG13 patient cells. We propose that decreased levels of mitochondrial proteases Lon and ClpP may allow Hsp60 substrate proteins to go through more folding attempts instead of being prematurely degraded, thereby supporting productive folding in cells with reduced Hsp60 chaperonin activity. In conclusion, our studies with SPG13 patient cells expressing the functionally impaired mutant Hsp60 chaperonin suggest that reduction of the degradative activity of the protein quality control system may represent a previously unrecognized cellular adaptation to reduced chaperone function.

Rare heterozygous parkin variants in French early-onset Parkinson disease patients and controls

BACKGROUND

Mutations in the parkin gene cause autosomal recessive early-onset parkinsonism. The effect of single heterozygous mutations in parkin is still unclear. The aim of this study was to evaluate the frequency of exonic parkin variants in a case-control study.

METHODS

The parkin gene was screened for both point mutations and exon rearrangements in 172 French patients with Parkinson disease (PD) and 170 controls from the same population. Patients with single parkin variants were also screened for PINK1, DJ-1 and LRRK2 exon 41 mutations.

RESULTS

10 exonic sequence variations were identified, including 3 known polymorphisms and 7 rare heterozygous variants, 2 of which were novel. There were significantly more rare heterozygous variants in patients (n = 10) with early-onset PD than in controls (n = 2). Screening of PINK1, DJ-1 and LRRK2 exon 41 in the 10 patients heterozygous for parkin failed to identify a second causative mutation.

CONCLUSION

These results suggest that single parkin mutations increase the risk of early-onset PD, but the possibility of a second parkin mutation cannot be excluded.

A new locus for autosomal recessive spastic paraplegia (SPG32) on chromosome 14q12-q21

Hereditary spastic paraplegias (HSPs) are a group of neurodegenerative disorders characterized by progressive spasticity of the lower limbs. Here, we performed a genome-wide linkage analysis on a consanguineous family presenting an autosomal recessive form of HSP associated with mild mental retardation, brainstem dysraphia, and clinically asymptomatic cerebellar atrophy. We have mapped the disease locus SPG32 to chromosome 14q12-q21 within a 30-cM interval, which excludes the atlastin gene.

Are interrupted SCA2 CAG repeat expansions responsible for parkinsonism?

BACKGROUND

Autosomal dominant parkinsonism (ADP) is caused in a large percentage of familial and sporadic cases by mutations in the LRRK2 gene, particularly G2019S. It is also caused by mutations in genes associated with autosomal dominant cerebellar ataxia (ADCA), notably CAG/CAA repeat expansions in SCA2.

METHODS

We screened 164 families with ADP for expansions in the SCA2, 3, and 17 genes and for the G2019S mutation in LRRK2. The SCA2 CAG/CAA repeat expansion was sequenced to determine its structure. The phenotypes of patients with ADP caused by the SCA2, LRRK2, and unknown mutations were compared, as well as those of SCA2 patients with interrupted or uninterrupted expansions of the same size.

RESULTS

Three French ADP families had SCA2 mutations. The expansions ranged from 37 to 39 repeats and were interrupted and stable upon transmission. All patients (n = 9) had levodopa-responsive parkinsonism without cerebellar signs. They had significantly more symmetric signs and less rigidity than ADP caused by the G2019S mutation in LRRK2 or by unknown mutations. Interestingly, two sisters carrying both the SCA2 and the G2019S LRRK2 mutations had markedly earlier onset than their mother with only SCA2. In contrast, similar-sized but uninterrupted repeats were associated with ADCA in which cerebellar ataxia was constant and associated only rarely with one or more mild parkinsonian signs.

CONCLUSION

These results suggest that the configuration of the SCA2 CAG/CAA repeat expansions plays an important role in phenotype variability. Uninterrupted SCA2 repeat expansions found in families with autosomal dominant cerebellar ataxia result in somatic mosaicism and produce large hairpin RNAs, which may interact with double-stranded RNA-binding proteins. These characteristics are modified by interruption of the SCA2 repeat expansion as found in families with autosomal dominant parkinsonism.

Muscle coenzyme Q10 deficiencies in ataxia with oculomotor apraxia 1

APTX gene mutations responsible for ataxia-oculomotor apraxia 1 (AOA1) were identified in a family previously reported with ataxia and coenzyme Q10 (CoQ10) deficiency. We measured muscle CoQ10 levels in six patients with AOA1 and found decreased levels in five. Patients homozygous for the W279X mutation had lower values (p = 0.003). A therapeutic trial of CoQ10 may be warranted in patients with AOA1.

Predominant dystonia with marked cerebellar atrophy: a rare phenotype in familial dystonia

BACKGROUND

Dystonia syndromes constitute a heterogeneous group of phenotypes that may be caused by different heredodegenerative, metabolic, or genetic diseases.

OBJECTIVE

To describe the characteristics of an unusual dystonia-plus phenotype associated with cerebellar atrophy.

METHODS

We selected patients with predominant dystonia and cerebellar atrophy among the 861 families referred to us for genetic testing from 1992 to 2003. The main secondary heredodegenerative causes and the major genes responsible for hereditary dystonias and autosomal dominant or recessive ataxias were excluded.

RESULTS

We identified 12 patients in 8 families with an unusual dystonia-plus phenotype characterized by dystonia and cerebellar atrophy on brain MRI. The mean age at onset was 27.3 +/- 11.5 years (range: 9 to 42 years) and the mean disease duration 14.7 +/- 7.7 years (range: 4 to 30). At onset, dystonia was focal or multifocal, mainly affecting vocal cords (n = 8) and upper limbs (n = 2). During the disease course spasmodic dysphonia became severe in five patients, leading to complete aphonia in two. Dystonia became generalized in five. Cerebellar ataxia was limited to unsteadiness in most patients and progressed very slowly. The paucity of clinical cerebellar signs contrasted with the marked cerebellar atrophy on brain MRI in most patients. Four families with two affected sibs support the hypothesis of an autosomal recessive disorder. However, X-linked inheritance is possible since only men were affected.

CONCLUSION

We have characterized an unusual familial phenotype associating dystonia and cerebellar atrophy in 12 male patients.

Scale for the assessment and rating of ataxia: development of a new clinical scale

OBJECTIVE

To develop a reliable and valid clinical scale measuring the severity of ataxia.

METHODS

The authors devised the Scale for the Assessment and Rating of Ataxia (SARA) and tested it in two trials of 167 and 119 patients with spinocerebellar ataxia.

RESULTS

The mean time to administer SARA in patients was 14.2 +/- 7.5 minutes (range 5 to 40). Interrater reliability was high, with an intraclass coefficient (ICC) of 0.98. Test-retest reliability was high with an ICC of 0.90. Internal consistency was high as indicated by Cronbach's alpha of 0.94. Factorial analysis revealed that the rating results were determined by a single factor. SARA ratings showed a linear relation to global assessments using a visual analogue scale, suggesting linearity of the scale (p < 0.0001, r(2) = 0.98). SARA score increased with the disease stage (p < 0.001) and was closely correlated with the Barthel Index (r = -0.80, p < 0.001) and part IV (functional assessment) of the Unified Huntington's Disease Rating Scale (UHDRS-IV) (r = -0.89, p < 0.0001), whereas it had only a weak correlation with disease duration (r = 0.34, p < 0.0002).

CONCLUSIONS

The Scale for the Assessment and Rating of Ataxia is a reliable and valid measure of ataxia, making it an appropriate primary outcome measure for clinical trials.