Clinical and molecular studies of 73 Italian families with autosomal dominant cerebellar ataxia type I: SCA1 and SCA2 are the most common genotypes

We clinically and genetically evaluated 73 Italian families with autosomal dominant cerebellar ataxia (ADCA) type I. Spinocerebellar ataxia (SCA) type 1 was the most common genotype (SCA1), accounting for 41% of cases (30 families), SCA2 was slightly less frequent (29%, 21 families), and the remaining families were negative for the SCA1, SCA2, and SCA3 mutations. Among the positively genotyped families, SCA1 was found most frequently in families from northern Italy (50%), while SCA2 was the most common mutation in families from the southern part of the country (56%). Slow saccades and decreased deep tendon reflexes were observed significantly more frequently in SCA2 patients, while increased deep tendon reflexes and nystagmus were more common in SCA1. In SCA1 and SCA2 families there was a significant inverse correlation between expansion size and age at onset. Analysis of triplet repeat numbers in parent-offspring pairs showed greater meiotic instability, which was associated with an earlier onset of the disease in SCA2 families than in SCA1 families. Received: 23 April 1998 Received in revised form: 14 September 1998 Accepted: 13 October 1998     

Spinocerebellar ataxia type 12 identified in two Italian families may mimic sporadic ataxia

SCA12 is an autosomal dominant cerebellar ataxia characterized by onset in the fourth decade of life with action tremor of arms and head, mild ataxia, dysmetria, and hyperreflexia. The disease is caused by an expansion of ≥51 CAGs in the 5′ region of the brain‐ specific phosphatase 2 regulatory subunit B‐beta isoform (PPP2R2B) gene. SCA12 is very rare, except for a single ethnic group in India. We screened 159 Italian ataxic patients for SCA12 and identified two families that segregated an expanded allele of 57 to 58 CAGs, sharing a common haplotype. The age at onset, phenotype, and variability of symptoms were compatible with known cases. In one family, the disease was apparently sporadic due to possible incomplete penetrance and/or late age at onset. Our data indicate that SCA12 is also present in Italian patients, and its genetic testing should be applied to both sporadic and familial ataxias. © 2010 Movement Disorder Society     

Spinocerebellar ataxia type 10: Frequency of epilepsy in a large sample of Brazilian patients

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder caused by an ATTCT repeat intronic expansion in the SCA10 gene. SCA 10 has been reported in Mexican, Brazilian, Argentinean and Venezuelan families. Its phenotype is overall characterized by cerebellar ataxia and epilepsy. Interestingly, Brazilian patients reported so far showed pure cerebellar ataxia, without epilepsy. Here, authors provide a systematic analysis of the presence, frequency and electroencephalographic presentation of epilepsy among 80 SCA10 patients from 10 Brazilian families. Overall, the frequency of epilepsy was considered rare, been found in 3.75 % of the cases while this finding in populations from other geographic areas reaches 60% of SCA10 cases. © 2010 Movement Disorder Society     

Spinocerebellar ataxia type 28: A novel autosomal dominant cerebellar ataxia characterized by slow progression and ophthalmoparesis

We have recently mapped the spinocerebellar ataxia type 28 (SCA28) locus on chromosome 18p11.22 in a four-generation Italian family. The clinical phenotype in affected individuals of this family was characterized by juvenile onset, slowly progressive gait and limb ataxia, dysarthria, hyperreflexia at lower limbs, nystagmus, and ophthalmoparesis. The mean age at onset was 19.5 years, and no evidence of anticipation between generations was observed. The disease locus on chromosome 18p11.22-q11.2 was found to span a region of 7.9 Mb of genomic DNA. Direct sequencing of candidate genes within the critical interval led to the identification of a heterozygous point mutation in one of them. The mutation was located in a highly conserved domain with proposed functional properties in the protein product of the SCA28 gene, and segregated with the disease phenotype in all affected members of this family. Thereafter we have screened 105 patients with autosomal dominant spinocerebellar ataxia who had resulted negative for mutations in known SCA genes. Genetic screening allowed the identification in a second Italian family of a distinct missense mutation located in the very same functional domain of the protein. The affected members of this second family exhibited a neurological phenotype similar to that of the original family. Both mutations, not found in more than 500 chromosomes, are associated with amino acid changes (Glu→Lys and Ser→Leu, respectively) in evolutionarily conserved residues of the alleged SCA28 gene. Our data point to a putative pathogenic role of these mutations, and indicate SCA28 as the sixth recognized SCA genotype caused by point mutations.     

Autosomal dominant cerebellar ataxia type I: oculomotor abnormalities in families with SCA1, SCA2, and SCA3

Forty-six patients suffering from autosomal dominant cerebellar ataxia type I (ADCA I) underwent to a genotype-phenotype correlation analysis by molecular genetic assignment to the spinocerebellar ataxia type 1, 2, or 3 (SCA1, SCA2, SCA3) genetic locus and electro-oculography. Oculomotor deficits that are attributed to dysfunction of cerebellar structures occurred in all three mutations without major differences between the groups. Gaze-evoked nystagmus, however, was not found to be associated with SCA2. Square wave jerks were exclusively observed in SCA3. The gain in vestibulo-ocular reflex was significantly impaired in SCA3 and SCA1. In SCA3 the severity of vestibular impairment increased with CAG repeat length. Severe saccade slowing was a highly characteristic feature of SCA2. In SCA3 saccade velocity was normal to mildly reduced while SCA1 fell into an intermediate range. The present data show that each mutation is associated with a distinct syndrome of oculomotor deficits. Reduced saccade velocity and the absence of both square-wave jerks and gaze-evoked nystagmus allow one SCA2 to be distinguished from SCA3 patients in almost all cases. The eye movement disorder of SCA1 patients, however, overlaps with both SCA2 and SCA3. Received: 9 September 1998 Received in revised form: 18 February 1999 Accepted: 23 February 1999     

Spinocerebellar ataxia type 17 (SCA17): Oculomotor phenotype and clinical characterization of 15 Italian patients

SCA17 is a rare type of autosomal dominant spinocerebellar ataxia caused by a CAG/CAA expansion in the gene encoding the TATA-binding protein (TBP).We screened for triplet expansion in the TBP gene 110 subjects with progressive cerebellar ataxia and 94 subjects with Huntington-like phenotype negative at specific molecular tests. SCA17 mutation-positive subjects were found in both groups of patients. Expanded alleles with ≥ 44 CAG/CAA repeats were identified in 11 individuals and in 4 non-symptomatic relatives. Eleven de novo diagnosed patients and four patients previously reported underwent extensive clinical, neuroradiological and oculographic examination. Cerebellar signs and symptoms were present in all cases; 80% of the patients had mild to severe cognitive deficits; 66% of patients showed choreic movements; pyramidal signs, bradykinesia and dystonia were observed in approx 50% of the cases. MRI demonstrated cortical and cerebellar atrophy in all patients, whereas neurophysiological examination excluded signs of peripheral nervous system involvement. Oculographic examinations were performed in 9 out of 15 patients and showed a distinct pattern of oculomotor abnormalities, characterized by impairment of smooth pursuit, defects in the saccade accuracy, normal saccade velocity, hyperreflexia of vestibuloocular reflexes, and absence of nystagmus. In summary, this study presents one of the largest series of SCA17 patients in Europe. In our group of patients, SCA17 represents the third most frequent SCA genotype. Our clinical data confirm the large variability in SCA17 phenotypic presentation, and indicate that a peculiar combination of neuroradiological, electrophysiological and oculomotor findings is recognizable in SCA17.     

CAG repeat length and clinical features in three Italian families with spinocerebellar ataxia type 2 (SCA2): early impairment of Wisconsin Card Sorting Test and saccade velocity

We report on the clinical, neuropsychological, neurophysiological, computerized eye movement, magnetic resonance imaging (MRI) and molecular findings from 17 individuals affected with spinocerebellar ataxia type 2 (SCA2) belonging to three families. The average age at onset of the symptoms was 35.6, 11.9 (mean, SD) years. The mean age at onset of the symptoms in the parents was 44.8, 8.2 years, and in the offspring it was 28.7, 7.2 years. In 12 parent-child pairs, the mean anticipation was –15.75, 9.1 years (range –8.1 to –23.3 years, t = –4.9, P = < 0.002). The mutated SCA2 alleles ranged from 38 to 42 CAG repeats, while the normal alleles ranged from 22 to 24 repeats, with 97% of the alleles having 22 repeats. Small differences in the number of CAG repeats influenced the age at onset and rate of progression of the disease considerably. Indeed, patients presenting with their first symptom at an age of 35 years or later with a slower course of the disease harboured between 38 and 39 repeats. In contrast, patients carrying ≥ 40 CAG repeats manifested the disease prior to 30 years of age and had a faster disease progression toward incapacity. The presenting symptom was always gait ataxia. Slow saccades occured from the beginning of the disease despite normal delay, accuracy and smooth pursuit eye movements. The neuropsychological study showed early and selective impairment of conceptual reasoning ability, as detected by the Wisconsin Card Sorting Test (WCST). It is noteworthy that a significant mutual relationship was observed between performance on the WCST and saccade velocity. All of these findings favour the hypothesis that the disease process of SCA2 in regions other than the cerebellum and brain stem affects severely and early those cortical structures involved in the control of both visually guided saccades and WCST performance. Received: 13 October 1997 Received in revised form: 23 February 1998 Accepted: 20 March 1998     

Frequency analysis and clinical characterization of different types of spinocerebellar ataxia in Serbian patients.

The relative frequencies of different spinocerebellar ataxias (SCAs) vary widely among different ethnic groups, presumably due to a founder effect. We investigated the relative prevalence of SCA1-3, 6-8, 12, 17; dentate-rubro-pallidoluysian atrophy; and Friedreich's ataxia (FRDA) in Serbian patients with adult-onset (>20 years of age) hereditary and sporadic SCAs, and compared clinical features of patients with genetically confirmed SCAs. A total of 108 patients from 54 families (38 apparently dominant [ADCA] and 16 apparently recessive) with adult-onset hereditary ataxia and 75 apparently sporadic patients were assessed. Of 38 families with ADCA, 13 (34%) were positive for an expansion in an SCA1 and 5 families (13%) for an expansion in an SCA2 allele. In 20 families (53%), no expansions have been identified in any of the analyzed genes. Gaze palsy, spasticity, and hyperreflexia were significantly more common in SCA1, whereas slow saccades, hypotonia, hyporeflexia, and dystonia prevailed in SCA2 patients. Among the 16 families with an apparently recessive mode of ataxia inheritance, 4 (25%) were identified as having the FRDA mutation. Ataxia-causing mutations were identified in 8 (10.6%) of patients with apparently sporadic adult-onset ataxia.     

Clinical features and natural history of spinocerebellar ataxia type 1

SCA1 is a dominant spinocerebellar ataxia (SCA) and a multi-systemic syndrome caused by abnormal expansion of unstable CAG repeat in a novel gene located on chromosome 6p22–p23. We clinically studied 35 Japanese SCA1 patients who were assumed to have come from a common origin. The age at onset ranged from 15–63 years, and significantly correlated with CAG repeat units of mutant alleles. Ataxia was the initial symptom, and the majority of patients had a similar history of signs and symptoms. Nystagmus was at first minimal, later attenuated, and a slow saccade followed. Limb tendon reflexes were mostly hyperactive and depressed with the development of diffuse amyotrophy. The cardinal feature was ataxia-hyperreflexia-late slow saccade syndrome with terminal amyotrophy. Although the phenotype of SCA1 overlaps with those of other dominant SCAs, some facets of the neurological events differ from either SCA2 with ataxia-hyporeflexia-slow saccade syndrome, or early-onset Machado-Joseph disease with dystonia-bradykinesia-spasticity syndrome.     

Clinical and genetic studies of spinocerebellar ataxia type 2 in Japanese kindreds

Objectives – We report the results of clinical and genetic studies from 2 related Japanese kindreds with spinocerebellar ataxia type 2 (SCA2). Material and methods – Family A showed 19 patients through 4 generations, while family B showed 6 patients, including dizygotic twin brothers, through 3 generations. We performed clinical, radiological, neurophysiological, and genetic analyses in the family members. Results – Neurologic analysis of 13 affected patients revealed a mean age at onset of 43.5 years. The most common neurologic finding was cerebellar ataxia with deep sensory disturbance. Slow saccades was found only in the younger patients below age 35 years. Nerve conduction studies revealed subclinical sensory neuropathy. Brain MRI showed the presence of pontocerebellar atrophy. Genetic study using PCR revealed that all affected patients had an expanded CAG allele in the ataxin-2 gene, which led to a final diagnosis of SCA2. Conclusion – SCA2 may be more clinically heterogeneous than previously thought. PCR is useful in differentiating SCA2 from other types of inherited ataxia.     

Spinocerebellar ataxia type 17 in the Yugoslav population

OBJECTIVES: (1) Analysis of Spinocerebellar ataxia type 17 (SCA17) locus in a group of ataxic patients excluded on other known SCAs; (2) assessment of frequency distributions of SCA17 alleles in the Yugoslav population. MATERIAL AND METHODS: Study includes 115 non-related Yugoslav patients belonging to autosomal-dominant cerebellar ataxias or to sporadic idiopathic adult-onset ataxia and 115 controls. Analysis of SCA17 locus was performed using polymerase chain reaction. RESULTS: None of the analyzed patients show the presence of mutation in SCA17 locus. In the group of patients 12 different alleles in the range of 30-42 repeats were observed, while in healthy population eight alleles in the range of 30-40 repeats were detected. CONCLUSION: (1) None of 115 non-related Yugoslav ataxic patients belong to any known SCAs nor to DRPLA gene; (2) the distribution of SCA17 alleles in the Yugoslav population is consistent with the distribution in other populations and (3) the paucity of alleles with more than 39 repeats could suggest that SCA17 is very rare in the Yugoslav population.     

Restless legs syndrome in spinocerebellar ataxia types 1, 2, and 3

To identify the prevalence and determinants of restless legs syndrome (RLS) in spinocerebellar ataxia (SCA) we studied 58 patients with a molecular diagnosis of SCA1, SCA2 and SCA3. Data on the symptoms of RLS were collected by a standardized questionnaire, and RLS was diagnosed when patients met the four minimal criteria of the syndrome as recently defined by an international study group. In addition, we studied the relationship between RLS and age, age at ataxia onset, CAG repeat length, and nerve conduction and evoked potentials data. RLS was significantly more frequent in SCA patients than in controls (28 % vs. 10 %). Age at RLS onset in SCA was 49.0 ± 10.9 years. There were no significant differences in nerve conduction or evoked potentials between RLS and non-RLS SCA patients. The probability of developing RLS increased with age but not with CAG repeat length or higher age of ataxia onset. The data provide evidence that patients with SCA1, SCA2 and SCA3 are per se more susceptible to RLS than non-affected individuals. The probability of developing RLS is related principally to the period over which the CAG repeat mutation exerts its effect and not to CAG repeat length or age of ataxia onset. Received: 18 July 2000, Received in revised form: 10 November 2000, Accepted: 15 November 2000     

Autosomal dominant cerebellar ataxia (SCA6): clinical, genetic and neuropathological study in a family

We describe a family with dominantly inherited ataxia of late adult onset. Expansion of a CAG repeat in the gene encoding the α_1A voltage-dependent calcium channel was identified at autopsy in one patient, a 65-year-old woman with a disease duration of 11 years. In this patient, pathological changes were confined to the cerebellar cortex and inferior olivary complex. The cerebellar cortex showed severe loss of Purkinje cells with proliferation of Bergmann’s glia, being more pronounced in the superior parts of the vermis and hemispheres. In the inferior olivary complex, a reduced neuronal cell population, which could be interpreted as a change secondary to the cerebellar cortical lesion, was evident. We conclude that the pathological phenotype of this newly classified autosomal dominant cerebellar ataxia, SCA6, is cerebello-olivary atrophy, or more strictly cerebellar cortical atrophy. Received: 27 May 1997 / Revised, accepted: 27 October 1997     

Spinocerebellar ataxias in Asia: Prevalence,phenotypes and management

This paper reviews and summarizes three main aspects of spinocerebellar ataxias (SCA) in the Asian population. First, epidemiological studies were comprehensively reviewed. Overall, the most common subtypes include SCA1, SCA2, SCA3, and SCA6, but there are large differences in the relative prevalence of these and other SCA subtypes between Asian countries. Some subtypes such as SCA12 and SCA31 are rather specific to certain Asian populations. Second, we summarized distinctive phenotypic manifestations of SCA patients of Asian origin, for example a frequent co-occurrence of parkinsonism in some SCA subtypes. Lastly, we have conducted an exploratory survey study to map SCA-specific expertise, resources, and management in various Asian countries. This showed large differences in accessibility, genetic testing facilities, and treatment options between lower and higher income Asian countries.Currently, many Asian SCA patients remain without a final genetic diagnosis. Lack of prevalence data on SCA, lack of patient registries, and insufficient access to genetic testing facilities hamper a wider understanding of these diseases in several (particularly lower income) Asian countries.     

Spinocerebellar ataxia type 17 is caused by mutations in the TATA-box binding protein

The spinocerebellar ataxia type 17 (SCA17) is characterized by cerebellar ataxia, dementia, and involuntary movements, including chorea and dystonia. In addition, psychiatric symptoms, pyramidal signs, and rigidity are common. MRI shows variable atrophy of the cerebrum, brainstem, and cerebellum. The autosomal dominantly inherited progressive neurodegenerative disorder is caused by an expanded CAA/CAG repeat coding for glutamine. Alleles of the normal range carry 25 to 42 glutamine residues, disease causing alleles 43 to 63. Alleles with 43 to 48 glutamine codons may be associated with incomplete penetrance. The mean age of onset is about 30 years for individuals with full-penetrance alleles, but ranges from three to 55 years.     

Spinocerebellar ataxia type 6 in eastern India: Some new observations

Introduction:Spinocerebellar ataxias (SCAs) are hereditary, autosomal dominant progressive neurodegenerative disorders showing clinical and genetic heterogeneity. They are usually manifested clinically in the third to fifth decade of life although there is a wide variability in the age of onset. More than 36 different types of SCAs have been reported so far and about half of them are caused by pathological expansion of the trinucleotide, Cytosine Alanine Guanine (CAG) repeat. The global prevalence of SCA is 0.3-2 per 100,000 population, SCA3 being the commonest variety worldwide, accounting for 20-50 per cent of all cases, though SCA 2 is generally considered as the commonest one in India. However, SCA6 has not been addressed adequately from India though it is common in the eastern Asian countries like, Japan, Korea and Thailand.Objective:The present study was undertaken to identify the prevalence of SCA6 in the city of Kolkata and the eastern part of India.Results:6 of the 83 subjects turned out positive for SCA6, constituting therefore, 13.33% of the patient pool.Discussion:SCA6 is prevalent in the eastern part of India, though not as frequent as the other common varieties.Conclusions:Further community based studies are required in order to understand the magnitude of SCA6 in the eastern part, as well as in other regions of India.     

Clinical and genetic analysis of three German kindreds with autosomal dominant cerebellar ataxia type I linked to the SCA2 locus

The detailed clinical, electrophysiological and imaging data of three German autosomal dominant cerebellar ataxia (ADCA) families are reported. Linkage to SCA2 was established using microsatellite markers D12S105, D12S1339(1328), D12S1340(1329) yielding a lod score exceeding +3.0 for the combined data. Analysis of the pedigree data provided evidence of anticipation as observed in other neurodegenerative disorders due to polyglutamine expansion encoded by a CAG repeat. This hypothesis was confirmed by the detection of the SCA2-specific pathological protein using the 1C2 monoclonal antibody which selectively recognizes large polyglutamine expansions and the characterization of a CAG expansion in the patients. Clinically, the families were characterized by progressive ataxia of stance, gait and limbs. Saccade velocity was markedly reduced in SCA2. Further oculomotor findings were gaze palsy, impaired smooth pursuit and reduced optokinetic reflex. Dementia and pyramidal tract signs were rather rare, while peripheral involvement (reduced or absent ankle reflexes, fasciculation-like movements, amyotrophy) was a prominent feature. Electrophysiological investigations provided evidence of sensory neuropathy of the axonal type and degeneration of the posterior columns. Imaging studies demonstrated severe shrinkage of brain-stem structures even in early stages of the disease. Received: 10 September 1996 Accepted: 8 December 1996     

Spinocerebellar ataxia type 6: CAG trinucleotide expansion, clinical characteristics and sperm analysis

Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant spinocerebellar degeneration caused by CAG repeat expansions in the human α1A voltage-dependent calcium channel subunit gene. We analyzed 16 SCA6 patients in 14 unrelated Japanese families, and documented the clinical and molecular properties correlating with the CAG repeat expansion. Three of them were sporadic. The CAG repeat number of the expanded and normal alleles was 22.7 ± 2.0 (mean ± SD, n = 15) and 13.8 ± 2.0 (n = 15), respectively, and the repeat size of the expanded alleles correlated inversely with age at onset. The patients presented here were clinically characterized by a slowly progressive cerebellar ataxia and nystagmus. In leukocytes, the strict pattern of the peak in the expanded allele on polyacrylamide gel electrophoresis did not show the presence of cell mosaicism in SCA6, in contrast to other trinucleotide disorders. Moreover, in each patient, the number of CAG repeats in sperm was the same as in leukocytes, and the expanded alleles in sperm indicated uniform peaks as well. In our geographic area, the frequency of SCA6 was as high as MJD, in contrast to the low frequency of other autosomal dominant cerebellar ataxias. Thus, a geographic difference in the frequency of autosomal dominant spinocerebellar ataxias may be present in Japan.     

Clinical and genetic study of a family with spinocerebellar ataxia type 1 (SCA1) and beta-thalassemia

We report a family affected by autosomal dominant ataxia, in which numerous members also showed microcytosis. Genetic analysis demonstrated a CAG expansion in the SCA1 locus in five members, while all subjects with microcytosis revealed a C-T substitution at codon 39 of the beta-globin gene. A pure cerebellar syndrome with prominent gait ataxia characterized the first stages of the neurological disease. The fully developed disease included additional clinical findings such as dysarthria and dysphagia, and instrumental signs of axonal involvement of the peripheral nerves. Ophthalmoplegia was not observed. The coexistence of hereditary spinocerebellar degeneration and erythropathies or hemoglobinopathies has been previously described. We discuss the possible linkages between these two pathologies.

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Sommario Riportiamo it caso di una famiglia affetta da atassia autosomica dominante, in cui numerosi membri presentavano anche microcitemia. L'analisi genetica dimostrava una espansione CA G net locus SCA1 in cinque membri, mentre tutti i soggetti con microcitemia erano portatori di una sostituzione C-T al codone 39 del gene delta beta-globina. La malattia neurologica era caratterizzata nelle prime fasi da una sindrome cerebellare pura con prevalente atassia delta marcia. Il quadro completo della malatia includeva anche disartria, disfagia e segni di danno assonale ai nervi periferici. Non veniva mai osservata oftalmoplegia. La coesistenza di degenerazione spinocerebellare ereditaria ed eritropatie o emoglobinopatie è già stata descritta precedentemente. Discutiamo i possibili legami tra queste due patologie.

     

Clinical and genetic analysis of spinocerebellar ataxia type 11

The autosomal dominant cerebellar ataxias (ADCAs) are a genetically heterogeneous group of disorders. Clinical classification of the ADCAs into three types has facilitated defining phenotypes and in turn, linkage analysis, which has led to the discovery of 30 loci and 16 genes. The type III ADCAs are ‘pure’ spinocerebellar ataxias (SCA), those that appear to elude neurological features outside of the cerebellum. At present 3 ADCA type III SCA genes have been published, SCA5, SCA6, and SCA14, these three genes appear to have various roles suggesting involvement in both different and possibly overlapping neurodegenerative pathways. The known ADCAIII genes are thought to have such roles as involvement in signal transduction, cell proliferation, synaptic transmission, and channel regulation. Here we update readers on the current progress on SCA11 and the identification of the disease gene. We discuss the clinical, genetic, and pathological details of SCA11 – a locus at chromosome 15q14-q21.3 in a Caucasian family of British ancestry. We also discuss the refining of this region, and methods used to prioritize the screening of the over 130 candidate genes in this genomic region.