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Background: Spinocerebellar ataxia type 8 (SCA8) is a dominantly inherited expansion disorder with highly variable penetrance. ATXN8OS/ATXN8 expanded alleles have been identified in association with other types of hereditary ataxias, pointing to a possible genetic synergism. Objectives: We aimed to further investigate the molecular background of patients with SCA8 diagnosis. Methods: Patients were selected from our cohort of 346 families. A total of 14 probands with SCA8 underwent additional investigation through exome sequencing. Results: Pathogenic heterozygous STUB1 variants were found in 21.4% of SCA8 patients (3 of 14) compared to only 0.5% in the non‐SCA8 group (1 of 222), indicating a statistically significant association (P < 0.05). Conclusions: The findings reported in this study might suggest a genetic synergism between STUB1 and ATXN8OS/ATXN8 expanded alleles. Further studies are needed to validate this observation and better define the clinical impact of this genetic interaction. [ABSTRACT FROM AUTHOR]

Cerebellar syndromes are clinically and etiologically heterogeneous and can be classified as hereditary, neurodegenerative non-hereditary, or acquired. Few data are available on the frequency of each form in the clinical setting. Growing interest is emerging regarding the genetic forms caused by triplet repeat expansions. Alleles with repeat expansion lower than the pathological threshold, termed intermediate alleles (IAs), have been found to be associated with disease manifestation. In order to assess the relevance of IAs as a cause of cerebellar syndromes, we enrolled 66 unrelated Italian ataxic patients and described the distribution of the different etiology of their syndromes and the frequency of IAs. Each patient underwent complete clinical, hematological, and neurophysiological assessments, neuroimaging evaluations, and genetic tests for autosomal dominant cerebellar ataxia (SCA) and fragile X-associated tremor/ataxia syndrome (FXTAS). We identified the following diagnostic categories: 28% sporadic adult-onset ataxia, 18% cerebellar variant of multiple system atrophy, 9% acquired forms, 9% genetic forms with full-range expansion, and 12% cases with intermediate-range expansion. The IAs were six in the FMR1 gene, two in the gene responsible for SCA8, and one in the ATXN2 gene. The clinical phenotype of patients carrying the IAs resembles, in most of the cases, the one associated with full-range expansion. Our study provides an exhaustive description of the causes of cerebellar ataxia, estimating for the first time the frequency of IAs in SCAs- and FXTAS-associated genes. The high percentage of cases with IAs supports further screening among patients with cerebellar syndromes. [ABSTRACT FROM AUTHOR]

Cerebellar dysfunction is likely to cause severe and treatment-resistant disability in multiple sclerosis (MS). Certain spinocerebellar ataxia (SCA)-related alleles can increase MS susceptibility, and channel polymorphisms can impact disability measures. Following an index patient with the coexistence of MS and SCA Type-8 (SCA8) in the MS clinic, an institutional engine search for MS and hereditary ataxia coexistence was conducted but did not reveal any other cases. This extremely rare coexistence of MS and SCA8 in our index patient may be incidental; however, a yet-to-be-identified contribution of coexistent hereditary ataxia(s) to the susceptibility of a prominent progressive ataxia MS phenotype cannot be ruled out. [ABSTRACT FROM AUTHOR]

Case reports: An elderly Chinese male patient was diagnosed with compound heterozygous spinocerebellar ataxia type 8; molecular diagnosis found that the (CTA)n(CTG)n repeat unit of his ATXN8/ATXN8OS gene was 134/93. The patient has a 6-year medical history, mainly manifested by ataxia, dysarthria, abnormal eye movements, and pyramidal signs. Magnetic resonance imaging (MRI) showed no obvious abnormalities in the medulla oblongata and cervical spinal cord except for cerebellar atrophy and sulci enlargement. There are heterozygous SCA8 individuals among his family members, but there are significant differences in their onset age and clinical manifestations. Discussion and conclusion: This case reminds us that (CTA)n(CTG)n repeats are very prone to dynamic mutations in intergenerational inheritance, and the ATXN8/ATXN8OS gene penetrance is different in different SCA8 individuals, which suggests that genetic detection is of great importance. [ABSTRACT FROM AUTHOR]

Abstract Background Spinocerebellar ataxia type 8 is an uncommon genetic condition and presents with gait disturbances, ataxia, dysarthria, nystagmus, and cognitive and psychiatric abnormalities. Seizures are extremely uncommon in the spinocerebellar ataxias and have been reported only once before in a patient with spinocerebellar ataxia type 8. This case report highlights the need to evaluate spells in patients with a known neurodegenerative or genetic disease to exclude seizures, and it stresses the importance of timely diagnosis and therapy. Case presentation The patient was a 22-year-old Caucasian woman with known spinocerebellar ataxia 8 since age 10 years. She was admitted to our hospital with new-onset left hemiparesis and encephalopathy in addition to chronic occurrence of multiple spells of confusion and oromanual automatisms with postictal lethargy. Testing confirmed that she was having recurrent seizures with episodes of nonconvulsive status epilepticus. Urgent treatment with antiepileptic therapy was initiated; her seizures resolved shortly thereafter, and her mental status improved. Her left hemiparesis has improved; she remains seizure-free; and she has returned to her baseline antiepileptic medications following physical therapy. Conclusions Seizures have been reported extremely rarely in association with spinocerebellar ataxia 8, but they must be considered in the differential diagnosis of patients with spells of altered awareness, especially in those with a known neurodegenerative or genetic condition. Clinicoradiological correlation with symptoms can help expedite diagnosis and treatment. Expert consultation with epileptologists at the earliest signs can help establish the diagnosis quickly, minimize morbidity, and enhance recovery.

Abstract Background Spinocerebellar ataxia (SCA) subtypes are often caused by expansions in non-coding regions of genes like SCA8, SCA10, SCA12 and SCA36. Other ataxias are known to be associated with repeat expansions such as fragile X-associated tremor ataxia syndrome (FXTAS) or expansions in the C9orf72 gene. When no mutation has been identified in the aforementioned genes next-generation sequencing (NGS)-based diagnostics may also be applied. In order to define an optimal diagnostic strategy, more information about the frequency and phenotypic characteristics of rare repeat expansion disorders associated with ataxia should be at hand. Methods We analyzed a consecutive cohort of 440 German unrelated patients with symptoms of cerebellar ataxia, dysarthria and other unspecific symptoms who were referred to our center for SCA diagnostics. They showed alleles in the normal range for the most common SCA subtypes SCA1-3, SCA6, SCA7 and SCA17. These patients were screened for expansions causing SCA8, SCA10, SCA12, SCA36 and FXTAS as well as for the pathogenic hexanucleotide repeat in the C9orf72 gene. Results Expanded repeats for SCA10, SCA12 or SCA36 were not identified in the analyzed patients. Five patients showed expanded SCA8 CTA/CTG alleles with 92-129 repeats. One 51-year-old male with unclear dementia symptoms was diagnosed with a large GGGGCC repeat expansion in C9orf72. The analysis of the fragile X mental retardation 1 gene (FMR1) revealed one patient with a premutation (>50 CGG repeats) and seven patients with alleles in the grey zone (41 to 54 CGG repeats). Conclusions Altogether five patients showed 92 or more SCA8 CTA/CTG combined repeats. Our results support the assumption that smaller FMR1 gene expansions could be associated with the risk of developing neurological signs. The results do not support genetic testing for C9orf72 expansion in ataxia patients.

Background: Spinocerebellar ataxia (SCA) subtypes are often caused by expansions in non-coding regions of genes like SCA8, SCA10, SCA12 and SCA36. Other ataxias are known to be associated with repeat expansions such as fragile X-associated tremor ataxia syndrome (FXTAS) or expansions in the C9orf72 gene. When no mutation has been identified in the aforementioned genes next-generation sequencing (NGS)-based diagnostics may also be applied. In order to define an optimal diagnostic strategy, more information about the frequency and phenotypic characteristics of rare repeat expansion disorders associated with ataxia should be at hand.Methods: We analyzed a consecutive cohort of 440 German unrelated patients with symptoms of cerebellar ataxia, dysarthria and other unspecific symptoms who were referred to our center for SCA diagnostics. They showed alleles in the normal range for the most common SCA subtypes SCA1-3, SCA6, SCA7 and SCA17. These patients were screened for expansions causing SCA8, SCA10, SCA12, SCA36 and FXTAS as well as for the pathogenic hexanucleotide repeat in the C9orf72 gene.Results: Expanded repeats for SCA10, SCA12 or SCA36 were not identified in the analyzed patients. Five patients showed expanded SCA8 CTA/CTG alleles with 92-129 repeats. One 51-year-old male with unclear dementia symptoms was diagnosed with a large GGGGCC repeat expansion in C9orf72. The analysis of the fragile X mental retardation 1 gene (FMR1) revealed one patient with a premutation (>50 CGG repeats) and seven patients with alleles in the grey zone (41 to 54 CGG repeats).Conclusions: Altogether five patients showed 92 or more SCA8 CTA/CTG combined repeats. Our results support the assumption that smaller FMR1 gene expansions could be associated with the risk of developing neurological signs. The results do not support genetic testing for C9orf72 expansion in ataxia patients. [ABSTRACT FROM AUTHOR]

Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated CaV2.1 (P/Q-type) and CaV3.2 (α1H T-type) calcium channels; KLHL1 knockdown experiments (KD) cause down-regulation of both channel types and altered synaptic properties in cultured rat hippocampal neurons (Perissinotti et al., 2014). Here, we studied the effect of ablation of KLHL1 on calcium channel function and synaptic properties in cultured hippocampal neurons from KLHL1 knockout (KO) mice. Western blot data showed the P/Q-type channel α1A subunit was less abundant in KO hippocampus compared to wildtype (WT); and PQ-type calcium currents were smaller in KO neurons than WT during early days in vitro, although this decrease was compensated for at late stages by increases in L-type calcium current. In contrast, T-type currents did not change in culture. However, biophysical properties and western blot analysis revealed a differential contribution of T-type channel isoforms in the KO, with CaV3.2 α1H subunit being down-regulated and CaV3.1 α1G up-regulated. Synapsin I levels were reduced in the KO hippocampus; cultured neurons displayed a concomitant reduction in synapsin I puncta and decreased miniature excitatory postsynaptic current (mEPSC) frequency. In summary, genetic ablation of the calcium channel modulator resulted in compensatory mechanisms to maintain calcium current homeostasis in hippocampal KO neurons; however, synaptic alterations resulted in a reduction of excitatory synapse number, causing an imbalance of the excitatory-inhibitory synaptic input ratio favoring inhibition.

Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltagegated CaV2.1 (P/Q-type) and CaV3.2 (α1H T-type) calcium channels; KLHL1 knockdown experiments (KD) cause down-regulation of both channel types and altered synaptic properties in cultured rat hippocampal neurons (Perissinotti et al., 2014). Here, we studied the effect of ablation of KLHL1 on calcium channel function and synaptic properties in cultured hippocampal neurons from KLHL1 knockout (KO) mice. Western blot data showed the P/Q-type channel α1A subunit was less abundant in KO hippocampus compared to wildtype (WT); and P/Q-type calcium currents were smaller in KO neurons than WT during early days in vitro, although this decrease was compensated for at late stages by increases in L-type calcium current. In contrast, T-type currents did not change in culture. However, biophysical properties and western blot analysis revealed a differential contribution of T-type channel isoforms in the KO, with CaV3.2 α1H subunit being down-regulated and CaV3.1 α1G up-regulated. Synapsin I levels were also reduced in the KO hippocampus and cultured neurons displayed a concomitant reduction in synapsin I puncta and decreased miniature excitatory postsynaptic current (mEPSC) frequency. In summary, genetic ablation of the calcium channel modulator resulted in compensatory mechanisms to maintain calcium current homeostasis in hippocampal KO neurons; however, synaptic alterations resulted in a reduction of excitatory synapse number, causing an imbalance of the excitatory-inhibitory synaptic input ratio favoring inhibition. [ABSTRACT FROM AUTHOR]

It has been reported that abnormal processing of pre- mRNA is caused by abnormal triplet expansion. Non-coding triplet expansions produce toxic RNA to alter RNA splicing activities. However, there has been no report on the globular RNA aggregation in neuronal cytoplasmic inclusions ( NCIs) up to now. We herein report on an autopsy case (genetically determined as spinocerebellar atrophy 8 ( SCA8)) with hitherto undescribed NCIs throughout the brain. NCIs were chiefly composed of small granular particles, virtually identical to ribosomes. Neurological features are comparable to the widespread lesions of the brain, including the spinal cord. Although 1C2-positivity of NCIs might be induced by reverse transcription of the CTG expansion, it remains to be clarified how abnormal aggregations of ribosome and extensive brain degeneration are related to the reverse or forward transcripts of the expanded repeat. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is an autosomal dominant disorder characterized by a triad of chorea, psychiatric disturbance and cognitive decline. Around 1% of patients with HD-like symptoms lack the causative HD expansion and are considered HD phenocopies. Genetic diseases that can present as HD phenocopies include HD-like syndromes such as HDL1, HDL2 and HDL4 (SCA17), some spinocerebellar ataxias (SCAs) and dentatorubral-pallidoluysian atrophy (DRPLA). In this study we screened a cohort of 21 Greek patients with HD phenocopy syndromes for mutations causing HDL2, SCA17, SCA1, SCA2, SCA3, SCA8, SCA12 and DRPLA. Fifteen patients (71%) had a positive family history. We identified one patient (4.8% of the total cohort) with an expansion of 81 combined CTA/CTG repeats at the SCA8 locus. This falls within what is believed to be the high-penetrance allele range. In addition to the classic HD triad, the patient had features of dystonia and oculomotor apraxia. There were no cases of HDL2, SCA17, SCA1, SCA2, SCA3, SCA12 or DRPLA. Given the controversy surrounding the SCA8 expansion, the present finding may be incidental. However, if pathogenic, it broadens the phenotype that may be associated with SCA8 expansions. The absence of any other mutations in our cohort is not surprising, given the low probability of reaching a genetic diagnosis in HD phenocopy patients. [ABSTRACT FROM AUTHOR]

Abstract: Spinocerebellar ataxia 8 (SCA8), a triplet repeat expansion disorder, is genetically distinct from the other inherited ataxias, but its unusually variable phenotype can make its diagnosis difficult. In this review we describe 3 new cases of genetically verified SCA8 to highlight the broad clinical spectrum of symptoms observed with this disorder and to draw attention to the features of myoclonus and migraine headaches, which in the context of cerebellar ataxia warrants the clinician to consider SCA8 as a potential diagnosis. We also address the controversy surrounding the genetic testing approach for diagnosing SCA8. Finally, we evaluate the evidence that SCA8 may affect calcium channel function and that the presentation of episodic ataxia and migraines suggests a clinical and pathogenic overlap of SCA8 with the channelopathies. [Copyright &y& Elsevier]

Abstract: We report a family with 16q-ADCA(16q 22.1 linked autosomal dominant cerebellar ataxia) coexisting with SCA8 repeat expansion. The brothers in this family presented with pyramidal signs, tremor, myoclonus and mental retardation in addition to cerebellar symptom in childhood. They showed both C-to-T substitution puratrophin-1 gene and an expanded allele of the SCA8 gene in the brothers and their father. These siblings presented with atypical symptoms and early onset age as16q-ADCA. Although it remains controversial whether the expanded SCA8 allele is associated with cerebellar symptoms, the coexistence of SCA8 repeat expansion with SCA6 was reported previously. Pure or predominant cerebellar symptoms were found in patients with SCA8, SCA6 and 16q-ADCA. In addition, common findings in neuropathology of SCA8, SCA6 and 16q-ADCA have been reported. We suppose that coexistence of SCA8 repeat expansion with 16q-ADCA may be involved in the pathogenesis and severe symptoms in this family. [Copyright &y& Elsevier]

Abstract: An increasing number of inherited neurodegenerative diseases are known to be caused by the expansion of unstable trinucleotide repeat tracts. Spinocerebellar ataxia type 8 (SCA8) has been identified as being partly caused by a CTG expansion in an untranslated, endogenous antisense RNA that overlaps the Kelch-like 1 (KLHL1) gene. Clinically, SCA8 patients show similar features to those with the other SCAs, including limb and truncal ataxia, ataxic dysarthria and horizontal nystagmus, all of which are signs of dysfunction of the cerebellar system. However, allele sizes within the SCA8 proposed pathogenic range have been reported in patients with ataxia of unknown etiology, in individuals from pedigrees with other SCA or Friedreich''s ataxia, and in patients with Alzheimer''s disease, schizophrenia or parkinsonism. These observations suggest that mutation of the SCA8 locus might affect neurons other than the cerebellum. Antisense transcripts are known to regulate complementary sense transcripts and are involved in several biologic functions, such as development, adaptive response, and viral infection. In order to test whether SCA8 affects the KLHL1 expression by antisense RNA in brain cells, we examined the expression pattern of KLHL1 and SCA8 in human tissues and in mouse brain regions. SCA8 expression was colocalized with KLHL1 transcript in many brain regions whose functions are correlated to the clinical symptoms of SCA8 patients. These findings lead to the hypothesis of a possible relevance that SCA8 transcript downregulates KLHL1 expression through an antisense mechanism, which then leads to SCA8 neuropathogenesis. [Copyright &y& Elsevier]

Abstract: We report two brothers with a progressive cerebellar syndrome due to spinocerebellar ataxia type 8 (SCA8). In addition to severe cerebellar atrophy, both had prominent white matter hyperintensities on cranial MRI. This is the first report of white matter hyperintensities on cranial MRI in patients with SCA8. A disorder due to a similar molecular basis, myotonic dystrophy 1 (DM1), is known to have white matter hyperintensities on cranial MRI. Cognitive impairment is well described in DM1 and is being recognized in SCA8. The significance of these associations is discussed. [Copyright &y& Elsevier]

Abstract: The actin-binding protein Kelch-like 1 (KLHL1) is a neuronal protein that belongs to the evolutionarily-conserved Kelch protein super-family. The mammalian KLHL1 is brain-specific, cytosolic and can form multimers and bind actin filaments. KLHL1’s function is likely that of an actin-organizing protein, possibly modulating neurite outgrowth, the dynamic morphology of dendritic spine heads; or anchoring proteins essential for post-synaptic function, like ion channels. Targeted deletion of the KLHL1 gene in Purkinje neurons results in dendritic deficits in these neurons, abnormal gait, and progressive loss of motor coordination in mice [He Y, Zu T, Benzow KA, Orr HT, Clark HB, Koob MD (2006) Targeted deletion of a single SCA8 ataxia locus allele in mice causes abnormal gait, progressive loss of motor coordination, and Purkinje cell dendritic deficits. J Neurosci 26:9975–9982]. Here we tested the hypothesis that KLHL1 may interact and modulate voltage-gated calcium channels by assessing the interaction of the principal subunit of P/Q-type channels, α1A, with KLHL1. Experiments in human embryonic kidney line HEK 293 (HEK) cells and cerebellar primary cultures revealed co-incidence of α1A and KLHL1 immunoreactivity when testing both the endogenous or epitope-tagged versions of the proteins. Similarly, co-immunoprecipitation experiments in HEK cells and brain tissue exposed the presence of KLHL1 in protein samples immunoprecipitated with FLAG-tagged or α1A antibodies. Functional studies of KLHL1 on P/Q-type current properties probed with whole-cell patch clamp revealed a significant increase in mean current density in the presence of KLHL1 (80% increase; from −13.2±2.0 pA/pF to −23.7±4.2 pA/pF, P<0.02), as well as a shift in steady state activation V50 of −5.5 mV (from 12.8±1.8 mV to 7.3±1.0 mV, P<0.02). Our data are consistent with a modulatory effect of KLHL1 on the P/Q-type calcium channel function and suggest a possible novel role for KLHL1 in cellular excitability. [Copyright &y& Elsevier]

Abstract: In the last ten years, several RNAs with no protein-coding potential have been accumulating in RNA databases and are in need of further molecular characterization. At the same time, examples of non-coding RNAs (ncRNAs) such as microRNAs, small RNAs, small interfering RNAs (siRNAs) and medium/large RNAs with various functions have been described in the literature. Recent evidence points to a widespread role of these molecules in eukaryotic cells, suggesting that the majority of the new ncRNA examples might have specific functions. The aim of this review is to describe several new functional ncRNAs that have been recently identified and characterized, providing some clues that these molecules might not be produced by chance or as by-products of transcription as has been speculated. [Copyright &y& Elsevier]

Spinocerebellar ataxia type 8 (SCA8) patients typically have a slowly progressive, adult-onset ataxia. SCA8 is dominantly inherited and is caused by large CTG repeat expansions in the untranslated antisense RNA of the Kelch-like 1 gene (KLHL1), but the molecular mechanism through which this expansion leads to disease is still unknown. To more fully characterize the underlying molecular mechanisms involved in SCA8, we developed a mouse model in which Klhl1 is deleted in either all tissues or is deleted specifically in Purkinje cells only. We found that mice that are either homozygous or heterozygous for the Klhl1 deletion have significant gait abnormalities at an early age and develop a significant loss of motor coordination by 24 weeks of age. This loss progresses more rapidly in homozygous knock-outs. Mice with Klhl1 specifically deleted in only Purkinje cells had a loss of motor coordination that was almost identical to the total-tissue deletion mice. Finally, we found significant Purkinje cell dendritic deficits, as measured by the thickness of the molecular layer, in all mice in which Klhl1 was deleted (both total and Purkinje cell-specific deletions) and an intermediate reduction in molecular layer thickness in mice with reduced levels of Klhl1 expression (heterozygous deletions). The results from this mouse model show that even a partial loss of Klhl1 function leads to degeneration of Purkinje cell function and indicates that loss of KLHL1 activity is likely to play a significant part in the underlying pathophysiology of SCA8. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Only a limited number of studies have investigated the cognitive performances of spinocerebellar ataxia (SCA) patients. In none of the SCA8 studies have the neuropsychological test performances been the primary measures. The objective of the current study was to investigate the characteristics of cognitive deficits in SCA8. Methods: Ten SCA8 patients and ten case-by-case matched control subjects underwent a comprehensive neuropsychological examination evaluating attention and information processing, concept formation, reasoning and executive functions, verbal production, memory and learning and visuoperceptual and -constructive functions. Results: SCA8 patients demonstrated deficits primarily in attention and information processing, as well as in concept formation, reasoning, executive functions and verbal production. Visuoperceptual and -constructive functions, as well as most of the performances of memory were unaffected. Conclusions: Cognitive impairments, especially those related to attention, information processing and executive functions, seem to be a clinical feature of SCA8 disease. [Copyright &y& Elsevier]

Controversial data have been reported about SCA8 since its description in 1999. The most accepted hypothesis is that CTG expansions within the CTA/CTG combined repeat expansion in the SCA8 locus causes SCA8. It is inherited as a dominant trait with reduced penetrance. The present study, reports the first data regarding SCA8 in the Spanish population and the clinical findings in patients carrying expanded alleles, including one homozygous patient. Two hundred and forty-six individuals from the Spanish population, including controls (149) and ataxic patients (97), were studied. DNA was extracted from blood samples using standard methods. Amplification of the CTA/CTG 3′untranslated region was achieved by PCR using primers SCA8-F3 and SCA8-R4 and conditions described previously. Neurological revaluation was done in individuals carrying the expanded allele. We detected five unrelated expanded alleles corresponding to three affected patients (one of them homozygous) and one healthy individual. SCA8 represents 4% of the total dominant spinocerebellar ataxias studied in our group (Spanish population) (three index patients out of 75 dominant ataxic independent nucleus). The patient that resulted homozygous for the expansion is a 25-year-old man with a clinical picture of progressive ataxia and dysarthria that began at the age of 12. On neurological examination, he showed ataxia, slight dysarthria and nystagmus to the extreme lateral gaze. A cranial MRI showed global atrophy of cerebellum but the brainstem was spared. Family history showed the presence of ataxia in his grandfather and father. His mother is healthy at the age of 52 and a molecular study of SCA8 reveals one allele that could be considered as premutated. She has no ataxia antecedents in her family. Our results provide additional information about the SCA8 expansion, within the Spanish population. These results are in agreement with the hypothesis of the CTG expansion in the SCA8 locus being... [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxia type 8 (SCA8) is a slowly progressive ataxia causally associated with untranslated CTG repeat expansion on chromosome 13q21. However, the role of the CTG repeat in SCA8 pathology is not yet well understood. Therefore, we studied the length of the SCA8 CTA/CTG expansions (combined repeats, CRs) in 115 patients with ataxia, 64 unrelated individuals with non-triplet neuromuscular diseases, 70 unrelated patients with schizophrenia, and 125 healthy controls. Only one patient with apparently sporadic ataxia was identified with an expansion of 100 CRs. He had inherited the expansion from his asymptomatic father (140 CRs) and transmitted the mutation to his son (92 CRs). Paternal transmission in this family produced contractions of 40 and 8 CRs, respectively. None of the subjects from other studied groups had an expansion at the SCA8 locus. In the control group the number of CRs at the SCA8 locus ranged from 14 to 34. Our findings support the notion that allelic variants of the expansion mutation at the SCA8 locus can predispose to ataxia. [ABSTRACT FROM AUTHOR]

Abstract: We report the case of a 29year old woman with a complex movement disorder syndrome due to the combination of coexisting pathological triplet repeat expansions of huntingtin and ATXN8 genes. The disease course was characterized by mental disturbances including cognitive decline and changes in personality starting at the age of 12years, followed by twisting motions, intentional tremor and gait ataxia. Later Parkinsonian symptoms of micrographia, bradykinesia, muscle rigidity and mental decline became dominant. Brain MRI showed hypoplasia of the nucleus caudatus and generalized atrophy; MR spectroscopy revealed a decrease of all typical metabolites except for an increased level of lactate and acetate. Therapeutic trials with pramipexole, ropinirole and tetrabenazine showed no benefit, while levetiracetam caused agitation and hallucinations. We discuss phenotype–genotype correlation and the rule of triplet repeat expansions of gene ATXN8. [Copyright &y& Elsevier]