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PubMed2003

Spinocerebellar ataxia type 6 and episodic ataxia type 2: differences and similarities between two allelic disorders.

Spinocerebellar ataxia type 6 (SCA6) is one of three allelic disorders caused by mutations of CACNA1A gene, coding for the pore-forming subunit of calcium channel type P/Q. SCA6 is associated with small expansions of a CAG repeat at the 3' end of the gene, while point mutations are responsible for its two allelic disorders (Episodic Ataxia type 2 and Familial Hemiplegic Migraine). Genetic, clinical, pathological and pathophysiological data of SCA6 patients are reviewed and compared to those of other SCAs with expanded CAG repeats as well as to those of its allelic channelopathies, with particular reference to Episodic Ataxia type 2. Overall SCA6 appears to share features with both types of disorders, and the question as to whether it belongs to polyglutamine disorders or to channelopathies remains unanswered at present.

Alleles↗
PubMed2002

A family with spinocerebellar ataxia type 8 expansion and vitamin E deficiency ataxia.

BACKGROUND: Ataxia with vitamin E deficiency is a recessive autosomal neurodegenerative disorder resembling the Friedreich ataxia phenotype but is due to mutations in the alpha-tocopherol transfer protein (TTPA) gene. In a recent article, we described a patient with ataxia carrying reduced serum vitamin E levels and showing CTA/CTG expansions of 320 triplet repeats in the SCA8 gene. OBJECTIVES: To perform a screening of the TTPA gene in the patient and to evaluate the effects of treatment with vitamin E on the patient's neurologic disturbances. PATIENT AND METHODS: We performed a single-strand conformation polymorphism and nucleotide sequence analysis of the 5 exons of the TTPA gene in the patient's family members. RESULTS: The results indicated the patient to be a compound heterozygote for 2 mutations (in exon 3), each transmitted by one of the 2 parents, yielding a nonfunctional protein. CONCLUSIONS: We describe for the first time, to our knowledge, a mutated form of the TTPA gene in a patient also carrying an expansion in the SCA8 gene. The lack of improvement in the patient's symptoms on supplementation with alpha-tocopherol suggests that the SCA8 mutations may act in the neurodegeneration process, worsening the neurologic signs caused by the vitamin E deficit, and it could be speculated that the co-occurrence of mutant alleles for 2 distinct loci may influence the clinical course of the disease.

Adult↗
PubMed2006

Reliability and validity of the International Cooperative Ataxia Rating Scale: a study in 156 spinocerebellar ataxia patients.

To evaluate the efficacy of treatments in spinocerebellar ataxias (SCAs), appropriate clinical scales are required. This study evaluated metric properties of the International Cooperative Ataxia Rating Scale (ICARS) in 156 SCA patients and 8 controls. ICARS was found to be a reliable scale satisfying accepted criteria for interrater reliability, test-retest reliability, and internal consistency. Although validity testing was limited, we found evidence of validity of ICARS when ataxia disease stages and Barthel index were used as external criteria. On the other hand, our study revealed two major problems associated with the use of ICARS. First, the redundant and overlapping nature of several items gave rise to a considerable number of contradictory ratings. Second, a factorial analysis showed that the rating results were determined by four different factors that did not coincide with the ICARS subscales, thus questioning the justification of ICARS subscore analysis in clinical trials.

Adolescent↗
PubMed1996

Brain levels of thiamine and its phosphate esters in Friedreich's ataxia and spinocerebellar ataxia type 1.

Decreased blood and cerebrospinal fluid levels of thiamine have been reported in patients with spinocerebellar ataxia disorders. To determine whether a thiamine deficiency is present in the brain, we measured levels of thiamine and its phosphate esters thiamine monophosphate (TMP) and thiamine diphosphate (TDP), in postmortem cerebellar and cerebral cortices of patients with Friedreich's ataxia (FA) and spinocerebellar ataxia type 1 (SCA1). Brain levels of free (nonphosphorylated) thiamine, TMP, TDP, and total thiamine in FA and SCA1 were, on average, not significantly different from control values. However, a nonsignificant trend was observed for slightly reduced levels of TDP and total thiamine in cerebellar cortex of the SCA1 patients, a finding that might be related to the severe neuronal damage in this brain area. We conclude that in FA, brain thiamine concentrations are normal, whereas in SCA1 the levels are, at most, only slightly reduced.

Adolescent↗
PubMed1996

Immunoreactive levels of alpha-ketoglutarate dehydrogenase subunits in Friedreich's ataxia and spinocerebellar ataxia type 1.

Enzyme activities of a alpha-ketoglutarate dehydrogenase complex (alpha KGDHC) and one of its constituent subunits, dihydrolipoamide dehydrogenase (E3), are reported to be reduced in non-CNS tissues of some patients with Friedreich's ataxia (FA); however, the results are highly conflicting. To determine whether an enzyme abnormality occurs in brain, we measured immunoreactive levels of the three alpha KGDHC subunits, namely, alpha-ketoglutarate dehydrogenase (E1), dihydrolipoamide succinyltransferase (E2) and E3 in postmortem frontal, occipital and cerebellar cortices of 18 control subjects, 9 patients with FA and, for comparison, 12 patients with spinocerebellar ataxia type 1 (SCA1). Decreased (-20 to -31%) levels of E3 were observed in all three examined areas of the patients with FA with the changes statistically significant in cerebellar and frontal cortices. The E3 reduction could be explained by a loss of alpha KGDHC or other dehydrogenase complexes (e.g. pyruvate dehydrogenase complex) which utilize this subunit. In SCA1, enzyme changes were limited to E2 in cerebellar (-26%) and frontal (-19%) cortices. Although the E3 and E2 reductions are only slight, and may represent secondary events, the changes in this key Krebs cycle enzyme could exacerbate degenerative processes in both of the spinocerebellar ataxia disorders.

Acyltransferases↗
PubMed1998

The complex clinical and genetic classification of inherited ataxias. I. Dominant ataxias.

The clinical classification of autosomal dominant cerebellar ataxias (ADCAs) is intricate due to the variable and unpredictable association of signs and symptoms of central nervous system (CNS) and peripheral nervous system (PNS) deterioration during the life of a patient. However, for many purposes, particularly patient management, clinical systematics is the most useful method for labelling patients; in some instances there is no basis for any more fundamental classification of phenotypes. On the other hand, recent molecular-genetic approaches to dominant ataxias have had a profound impact in nosology, diagnostic procedures and the management of patients, since they are based on the fact that all mendelian neurological diseases can be precisely classified according to the locus involved as well as the particular mutant allele at that locus. Therefore, a clinical and genetic classification of dominant ataxias is herewith proposed as the best nosographical choice. Clinical, neuropathological, genetic, and pathogenetic aspects of ADCAs are reviewed and discussed to help the clinical neurologist guide diagnostic procedures and manage ataxic patients.

Cerebellar Ataxia↗
PubMed2006

Infantile spinocerebellar ataxia type 6: relationship to episodic ataxia type 6.

Spinocerebellar ataxia type 6 is one of the hereditary progressive cerebellar ataxias first described in 1997. Genetic studies have identified the defect as abnormal expansion of CAG trinucleotide repeat in 1 alpha subunit of the calcium channel gene located on chromosome 19p13. The symptomatic individuals have 20 or 23 repeats in contrast to normal individuals who manifest 19 or less CAG repeats. Most of the earlier reports indicate the age of onset of symptoms to be after the third decade. This report presents a patient with episodic symptoms soon after birth, which is unusual, and to our knowledge this is the youngest reported case. The clinical features of spinocerebellar ataxia type 6 are variable. The mode of inheritance and the common symptoms of this condition are also discussed.

Acetazolamide↗
PubMed2001

Spinocerebellar ataxia type 7: a distinctive form of autosomal dominant cerebellar ataxia with retinopathy and marked genetic anticipation.

When a child presents with progressive ataxia, there is a broad differential diagnosis and a very long list of potential investigations. Spinocerebellar ataxia type 7 presenting in infancy is a rare condition where a presumptive diagnosis can be made based on the clinical features alone. These include rapidly progressive ataxia, retinopathy and autosomal dominant inheritance with marked genetic anticipation of paternal origin. The father of the infant may manifest minimal symptoms at a time when the infant is severely affected. Diagnosis is confirmed by the demonstration of an expansion of a CAG repeat in the coding region of the gene on chromosome 3p. We present a case to illustrate the diagnostic difficulties. Antenatal diagnosis was performed in two subsequent pregnancies.

Fatal Outcome↗
PubMed2001

Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia.

We have investigated the functional consequences of three P/Q-type Ca(2+) channel alpha1A (Ca(v)2.1alpha(1)) subunit mutations associated with different forms of ataxia (episodic ataxia type 2 (EA-2), R1279Stop, AY1593/1594D; progressive ataxia (PA), G293R). Mutations were introduced into human alpha1A cDNA and heterologously expressed in Xenopus oocytes or tsA-201 cells (with alpha(2)delta and beta1a) for electrophysiological and biochemical analysis. G293R reduced current density in both expression systems without changing single channel conductance. R1279Stop and AY1593/1594D protein were expressed in tsA-201 cells but failed to yield inward barium currents (I(Ba)). However, AY1593/1594D mediated I(Ba) when expressed in oocytes. G293R and AY1593/1594D shifted the current-voltage relationship to more positive potentials and enhanced inactivation during depolarizing pulses (3 s) and pulse trains (100 ms, 1 Hz). Mutation AY1593/1594D also slowed recovery from inactivation. Single channel recordings revealed a change in fast channel gating for G293R evident as a decrease in the mean open time. Our data support the hypothesis that a pronounced loss of P/Q-type Ca(2+) channel function underlies the pathophysiology of EA-2 and PA. In contrast to other EA-2 mutations, AY1593/1594D and G293R form at least partially functional channels.

Amino Acid Sequence↗
PubMed2000

Mapping of spinocerebellar ataxia 13 to chromosome 19q13.3-q13.4 in a family with autosomal dominant cerebellar ataxia and mental retardation.

We examined a large French family with autosomal dominant cerebellar ataxia (ADCA) that was excluded from all previously identified spinocerebellar ataxia genes and loci. The patients-seven women and a 4-year-old boy-exhibited slowly progressive childhood-onset cerebellar gait ataxia associated with cerebellar dysarthria, moderate mental retardation (IQ 62-76), and mild developmental delays in motor acquisition. Nystagmus and pyramidal signs were also observed in some cases. This unique association of clinical features clearly distinguishes this new entity from other previously described ADCA. Cerebral magnetic-resonance imaging showed moderate cerebellar and pontine atrophy in two patients. We performed a genomewide search and found significant evidence for linkage to chromosome 19q13.3-q13.4, in an approximately 8-cM interval between markers D19S219 and D19S553.

Adult↗
PubMed1997

Japanese families with autosomal dominant pure cerebellar ataxia map to chromosome 19p13.1-p13.2 and are strongly associated with mild CAG expansions in the spinocerebellar ataxia type 6 gene in chromosome 19p13.1.

Autosomal dominant cerebellar ataxia is a group of clinically and genetically heterogeneous disorders. We carried out genomewide linkage analysis in 15 families with autosomal dominant pure cerebellar ataxia (ADPCA). Evidence for linkage to chromosome 19p markers was found in nine families, and combined multipoint analysis refined the candidate region to a 13.3-cM interval in 19p13.1-p13.2. The remaining six families were excluded for this region. Analysis of CAG-repeat expansion in the alpha1A-voltage-dependent calcium channel (CACNL1A4) gene lying in 19p13.1, recently identified among 8 small American kindreds with ADPCA (spinocerebellar ataxia type 6 [SCA6]), revealed that 8 of the 15 families studied had similar, very small expansion in this gene: all affected individuals had larger alleles (range of CAG repeats 21-25), compared with alleles observed in neurologically normal Japanese (range 5-20 repeats). Inverse correlation between the CAG-repeat number and the age at onset was found in affected individuals with expansion. The number of CAG repeats in expanded chromosomes was completely stable within each family, which was consistent with the fact that anticipation was not statistically proved in the SCA6 families that we studied. We conclude that more than half of Japanese cases of ADPCA map to 19p13.1-p13.2 and are strongly associated with the mild CAG expansion in the SCA6/CACNL1A4 gene.

Adult↗
PubMed2005

The occurrence of dominant spinocerebellar ataxias among 251 Finnish ataxia patients and the role of predisposing large normal alleles in a genetically isolated population.

OBJECTIVES: Frequency and distribution of dominant ataxias caused by dynamic mutations may vary in different populations, which has been explained on the basis of relative frequency of predisposing normal alleles. The aim of the study was to evaluate the occurrence of spinocerebellar ataxias (SCAs) and dentatorubral-pallidoluysian atrophy (DRPLA) in Finland, and to investigate the role of predisposing normal alleles in a genetically homogenous population. MATERIAL AND METHODS: Mutation analyses for SCA1, 2, 3, 6, 7, 8, 10, 12, 17, and DRPLA and frataxin genes were performed for 251 unrelated Finnish patients who presented with progressive ataxia disorder. RESULTS: Expansions of SCA1, SCA2, SCA6, SCA7, SCA8, and SCA17 genes were detected in 2, 1, 1, 7, 22, and 1 patients, respectively. Altogether, 39 and 7% of dominant and sporadic SCA patients, respectively, harboured expansions at some of the investigated loci. Normal variation, collected from 477 to 502 chromosomes at each disease loci, revealed that Finns were different from the Japanese but largely similar to other Caucasians. CONCLUSIONS: Lack of SCA3 and excess of SCA8 are characteristic to the Finnish population. Homozygosity for the SCA8 expansion increases penetrance. Frequencies of large normal alleles at the SCA loci predict poorly prevalence of the respective diseases in Finland. Prioritization in DNA testing, based on ethnic origin and geographical location, is recommendable in Finland, and analogous approach may be applied to other countries as well.

Ataxin-1↗
PubMed2001

Spinocerebellar ataxia type 6 and episodic ataxia type 2 in a Korean family.

Spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2) and familial hemiplegic migraine (FHM) have been known as allelic disorders, which are caused by the alteration of the alpha1A voltage-dependent calcium channel subunit. Expansions of the CAG repeat in the CACNA1A gene on the short arm of the chromosome 19 induce SCA6, and point mutations in the same gene are responsible for EA2 and FHM. In recent studies, both SCA6 and EA2 have been concurrently found in families with 26 CAG repeats without previously reported point mutations either in coding sequences or in intron-exon junctions. We describe a Korean family with CAG26 repeats in the CACNA1A gene. Some of the affected family members had progressive ataxia typical of SCA6 whereas others had episodic vertigo responsive to acetazolamide typical of EA2. Our family support that SCA6 and EA2 are allelic disorders with a high phenotypic variability.

Adolescent↗
PubMed1985

[An autopsy case of hereditary ataxia (hereditary spastic ataxia)].

An autopsy case of hereditary spastic ataxia is reported. There are four family members with similar symptomatology through three generations. A 36-year-old man developed atactic gait at the age of 22 years, with following dysarthria, scanning speech, pyramidal signs, dysmetria, dysdiadochokinesia, nystagmus and mild sensory disturbance. The clinical course was steadily progressive and terminated about 14 years after the onset. The gross examination showed smallness of the brain stem and spinal cord with marked symmetrical atrophy of the anterior and lateral columns, especially at thoracic level. Histologically, pronounced degeneration was found in the anterior and posterior spino-cerebellar tracts, spino-thalamic tracts, and spinal ganglia. The olivary nuclei, pons and cerebellum were spared. The dentate nuclei showed considerable loss of neurons with degeneration, however there were no clinical signs related to this pathology. This case is considered to fall in the group of hereditary spastic ataxia according to Greenfield's classification, however, there was no report on degeneration of the dentate nucleus in this disease for the present. Hereditary spastic ataxia is very rare disease and only four cases have well been documented in our country to the best of our knowledge. The presence of nystagmus and superficial sensory disturbance, and sparing of the posterior column of the spinal cord seems to be common clinico-pathology in Japanese cases, differing from those of foreign cases. The fact that reactive astrogliosis was immunohistochemistry demonstrated in the degenerative regions of the spinal cord and where is no discrepancy between degenerative and reparative processes as reported before is stressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Autosomal dominant cerebellar ataxia type I linked to chromosome 12q (SCA2: spinocerebellar ataxia type 2).

Spinocerebellar ataxia 2 (SCA2) is one of the loci for the clinically and genetically heterogeneous group of autosomal dominant type I cerebellar ataxias. After initial linkage to chromosome 12q in Cuban families, SCA2 was shown to be the gene responsible for the disease in Italian, Tunisian, French-Canadian, Austrian-Canadian and Martinican kindreds with dominant ataxia, and the candidate interval was reduced to 6.4 cM between markers D12S84 and D12S79. Comparison of patients from families of different geographical origins clearly demonstrates the clinical interfamilial variability of the clinical signs which reaches statistical significance for the frequency of extrapyramidal rigidity, postural tremor and dementia. The most striking difference between the 29 Martinican SCA2 patients and those with SCA1 on chromosome 6p or SCA3/MJD on chromosome 14q is the greater frequency of hyporeflexia in the former. A mean 12.5 year anticipation is observed, with a more rapid clinical course of the disease in successive generations, indicating that an expanded trinucleotide repeat probably constitutes the underlying molecular mechanism.

Adolescent↗
PubMed1997

Brain regional differences in the expansion of a CAG repeat in the spinocerebellar ataxias: dentatorubral-pallidoluysian atrophy, Machado-Joseph disease, and spinocerebellar ataxia type 1.

Three autosomal dominant spinocerebellar ataxias, dentatorubral-pallidoluysian atrophy (DRPLA), Machado-Joseph disease (MJD), and spinocerebellar ataxia type 1 (SCA1), are associated with the expansion of a CAG repeat in the respective genes. To investigate the association between CAG repeat expansion and neuropathological findings, we analyzed several brain regions from 9 cases of DRPLA, 3 cases of MJD, and 1 case of SCA1. We found that the expanded alleles were smaller in the cerebellar cortex than in other brain regions, such as the frontal cortex, in these three diseases. The discrepancy in the expanded CAG repeat length between cerebellar cortex and other tissues was most prominent in DRPLA, and especially in cases of adult-onset DRPLA. A significant correlation was found between the age at onset of DRPLA and the size of the CAG repeat expansion. Cerebella of DRPLA patients were microscopically dissected into three layers, the molecular and granular layers and the white matter, which were analyzed separately. The lower level of CAG repeat expansion in DRPLA cerebella was representative of CAG repeat expansion in the granule cells. The microdissected samples of the granular layer of the hippocampal formation, which is densely packed with neuronal cells, revealed that the degree of CAG repeat expansion in this layer was similar to that in the cerebellum. These observations suggest that granule cells in the cerebellum and hippocampus have low levels of CAG repeat expansion, and that other types of cells exhibit a higher level of CAG repeat expansion, in spinocerebellar ataxias.

Adolescent↗
PubMed1998

Reduced immunoreactivity to calcium-binding proteins in Purkinje cells precedes onset of ataxia in spinocerebellar ataxia-1 transgenic mice.

Earlier we have shown alterations in immunoreactivity (IR) to the calcium-binding proteins parvalbumin (PV) and calbindin D-28k (CaB) in surviving Purkinje cells of patients with spinocerebellar ataxia-1 (SCA-1). In the present study we determined PV and CaB expression (by immunohistochemical and immunoblot analyses) in Purkinje cells of transgenic mice (TM) expressing the human SCA-1 gene with an expanded (line B05) and normal (line A02) CAG tract, as well as in age-matched nontransgenic mice (nTM). Heterozygotes in the B05 line develop progressive ataxia beginning around 12 weeks of age. A02 animals are phenotypically indistinguishable from wild-type (nontransgenic) animals. In the cerebella of 8-, 9-, and 12-week-old TM-B05 there was a progressive decrease in PV IR in Purkinje cells compared with nTM and TM-A02. Parvalbumin immunostaining in interneurons was well preserved in all groups. A progressive decrease was also observed in CaB IR in Purkinje cells of 8-, 9-, and 12-week-old TM-B05. Cerebellar Purkinje cells of 6-week-old TM-B05, which exhibit no ataxia and even lack demonstrable Purkinje cell loss, also revealed reduction in PV IR. This change was matched by a significant decrease in the amount of cerebellar PV in 6-week-old TM-B05 as determined by Western blot analysis. Calbindin D-28K immunohistochemistry did not detect any marked changes in CaB IR within Purkinje cells at 4 weeks. However, at 6 weeks immunostaining and immunoblot analysis revealed a significant decrease in CaB in TM-B05 compared with controls. These data suggest that decreased levels of calcium-binding proteins in Purkinje cells in SCA-1 transgenic mice may cause alteration in Ca2+ homeostasis.

Alleles↗
PubMed1997

The CAG repeats number of spinocerebellar ataxia type 1 gene in normal Taiwanese and in patients with dominant inherited ataxia.

Spinocerebellar ataxia type 1 (SCA 1) is an autosomal dominant disorder characterized by neurodegeneration of the cerebellum, spinal cord and brainstem. This neurodegeneration disease is associated with expansion of unstable CAG repeats within the coding region of the gene. We are conducting a local survey of the normal population and candidate patients to analyze the CAG repeats in SCA 1 gene. So far, we have collected peripheral blood from 78 normal individuals and 10 patients with dominant inherited ataxia disorders, and assayed the SCA1 CAG trinucleotide repeat using genomic polymerase chain reaction (PCR). Even though no local SCA 1 patients have been identified, we have established the distributions of the CAG repeat units of SCA 1 gene in the normal population in Taiwan. The normal range of CAG repeats is from 22 to 33 repeats, with the most common being 30 repeats. The range is relatively narrow compared to that reported for other ethnic groups. In addition, direct genomic PCR analysis of the SCA 1 gene from villous DNA has been successful in our laboratory. Screening of SCA 1 patients from patients with dominant inherited ataxia is currently underway in our laboratory. Here, we demonstrate that our molecular analysis technique makes possible the quick and accurate diagnosis of SCA1 patients and prenatal screening for SCA 1 families.

Ataxin-1↗