Safety and Efficacy of Acetyl-DL-Leucine in Certain Types of Cerebellar Ataxia: The ALCAT Randomized Clinical Crossover Trial

IMPORTANCE

Cerebellar ataxia is a neurodegenerative disease impairing motor function characterized by ataxia of stance, gait, speech, and fine motor disturbances.

OBJECTIVE

To investigate the efficacy, safety, and tolerability of the modified essential amino acid acetyl-DL-leucine in treating patients who have cerebellar ataxia.

DESIGN, SETTING, AND PARTICIPANTS

The Acetyl-DL-leucine on Cerebellar Ataxia (ALCAT) trial was an investigator-initiated, multicenter, double-blind, randomized, placebo-controlled, clinical crossover trial. The study was conducted at 7 university hospitals in Germany and Austria between January 25, 2016, and February 17, 2017. Patients were aged at least 18 years and diagnosed with cerebellar ataxia of hereditary (suspected or genetically confirmed) or nonhereditary or unknown type presenting with a total score of at least 3 points on the Scale for the Assessment and Rating of Ataxia (SARA). Statistical analysis was performed from April 2018 to June 2018 and January 2020 to March 2020.

INTERVENTIONS

Patients were randomly assigned (1:1) to receive acetyl-DL-leucine orally (5 g per day after 2 weeks up-titration) followed by a matched placebo, each for 6 weeks, separated by a 4-week washout, or vice versa. The randomization was done via a web-based, permuted block-wise randomization list (block size, 2) that was stratified by disease subtype (hereditary vs nonhereditary or unknown) and site.

MAIN OUTCOMES AND MEASURES

Primary efficacy outcome was the absolute change of SARA total score from (period-dependent) baseline to week 6.

RESULTS

Among 108 patients who were randomly assigned to sequence groups (54 patients each), 55 (50.9%) were female; the mean (SD) age was 54.8 (14.4) years; and the mean (SD) SARA total score was 13.33 (5.57) points. The full analysis set included 105 patients (80 patients with hereditary, 25 with nonhereditary or unknown cerebellar ataxia). There was no evidence of a difference in the mean absolute change from baseline to week 6 in SARA total scores between both treatments (mean treatment difference: 0.23 points [95% CI, -0.40 to 0.85 points]).

CONCLUSIONS AND RELEVANCE

In this large multicenter, double-blind, randomized, placebo-controlled clinical crossover trial, acetyl-DL-leucine in the investigated dosage and treatment duration was not superior to placebo for the symptomatic treatment of certain types of ataxia. The drug was well tolerated; and ALCAT yielded valuable information about the duration of treatment periods and the role of placebo response in cerebellar ataxia. These findings suggest that further symptom-oriented trials are needed for evaluating the long-term effects of acetyl-DL-leucine for well-defined subgroups of cerebellar ataxia.

TRIAL REGISTRATION

EudraCT 2015-000460-34.

The Classification of Autosomal Recessive Cerebellar Ataxias: a Consensus Statement from the Society for Research on the Cerebellum and Ataxias Task Force

There is currently no accepted classification of autosomal recessive cerebellar ataxias, a group of disorders characterized by important genetic heterogeneity and complex phenotypes. The objective of this task force was to build a consensus on the classification of autosomal recessive ataxias in order to develop a general approach to a patient presenting with ataxia, organize disorders according to clinical presentation, and define this field of research by identifying common pathogenic molecular mechanisms in these disorders. The work of this task force was based on a previously published systematic scoping review of the literature that identified autosomal recessive disorders characterized primarily by cerebellar motor dysfunction and cerebellar degeneration. The task force regrouped 12 international ataxia experts who decided on general orientation and specific issues. We identified 59 disorders that are classified as primary autosomal recessive cerebellar ataxias. For each of these disorders, we present geographical and ethnical specificities along with distinctive clinical and imagery features. These primary recessive ataxias were organized in a clinical and a pathophysiological classification, and we present a general clinical approach to the patient presenting with ataxia. We also identified a list of 48 complex multisystem disorders that are associated with ataxia and should be included in the differential diagnosis of autosomal recessive ataxias. This classification is the result of a consensus among a panel of international experts, and it promotes a unified understanding of autosomal recessive cerebellar disorders for clinicians and researchers.

Current and Promising Therapies in Autosomal Recessive Ataxias

BACKGROUND & OBJECTIVE

Ataxia is clinically characterized by unsteady gait and imbalance. Cerebellar disorders may arise from many causes such as metabolic diseases, stroke or genetic mutations. The genetic causes are classified by mode of inheritance and include autosomal dominant, X-linked and autosomal recessive ataxias. Many years have passed since the description of the Friedreich's ataxia, the most common autosomal recessive ataxia, and mutations in many other genes have now been described. The genetic mutations mostly result in the accumulation of toxic metabolites which causes Purkinje neuron lost and eventual cerebellar dysfunction. Unfortunately, the recessive ataxias remain a poorly known group of diseases and most of them are yet untreatable.

CONCLUSION

The aim of this review is to provide a comprehensive clinical profile and to review the currently available therapies. We overview the physiopathology, neurological features and diagnostic approach of the common recessive ataxias. The emphasis is also made on potential drugs currently or soon-to-be in clinical trials. For instance, promising gene therapies raise the possibility of treating differently Friedreich's ataxia, Ataxia-telangiectasia, Wilson's disease and Niemann-Pick disease in the next few years.

[Recent advance in genetic study of hereditary autosomal recessive cerebellar ataxia]

Autosomal recessive cerebellar ataxias (ARCA) are a highly heterogeneous group of rare neurodegenerative diseases affecting both central and peripheral nervous systems. Based on pathological mechanisms, five major types of ARCA may be distinguished, which include mitochondrial ataxia, metabolic disorder, DNA repair defect ataxia, congenital ataxias and degenerative ataxia. This review summarizes clinical features, molecular genetics and recent advances in DNA sequencing of common types of ARCA.

Altered soleus responses to magnetic stimulation in pure cerebellar ataxia

OBJECTIVE

Transcranial magnetic stimulation (TMS) over the leg motor area elicits a soleus primary response (SPR) and a soleus late response (SLR). We evaluated the influence of the cerebellofugal pathway on the SPR and SLR in patients with 'pure' cerebellar ataxia.

METHODS

SPRs and SLRs were recorded from 11 healthy subjects and 9 patients with 'pure' cerebellar cortical degeneration; 5 with spinocerebellar ataxia type 6 (SCA6), and 4 with late cortical cerebellar ataxia (LCCA). In addition, three patients with localized cerebellar lesions were tested.

RESULTS

The SPR latency was significantly longer in patients than in controls, but primary responses in the tibialis anterior muscle were normal. The frequency of abnormal SLR was 38.9% in the supine position and 83.3% in the standing position. Two out of three patients with localized cerebellar lesions also showed abnormal SLR.

CONCLUSIONS

Altered SPRs in patients may result from a dysfunction of the primary motor cortex caused by crossed cerebello-cerebral diaschisis. In addition, our results suggest that 'pure' cerebellar degeneration involves the mechanism responsible for evoking SLR which is related to the control of posture.

SIGNIFICANCE

SLR can be a useful neurophysiological parameter for evaluating cerebellofugal function.

[Non-progressive congenital ataxias]

INTRODUCTION

Non-progressive congenital ataxias (NPCA) constitute a heterogeneous group of processes linked to diverse aetiological factors that can be either environmentally or genetically determined. The signs of cerebellar compromise, which are preceded by unspecific signs such as early hypotonia, difficulty in sucking or chewing or retarded motor acquisition, become apparent with development or may remain absent when the disorder is very severe.

DEVELOPMENT

NPCA can be accompanied by a number of pathologies and their diagnosis can be made easier by the concurrence of symptoms or signs of extra-cerebellar involvement, such as dysmorphic features or abnormalities affecting the skin, heart, bones, blood, eyes or other areas of the central or peripheral nervous system. Neuroimaging usually reveals vermian hypoplasia and/or hypoplasia of the cerebellar hemispheres, but can be normal in certain situations. The article includes a review of the NPCA following the classification proposed by Steinlin in 1998.

CONCLUSIONS

The difficulties inherent in diagnosing these processes makes it necessary to deploy a wide range of complementary examinations, especially metabolic tests, before a generic diagnosis of NPCA can be established. Although the progress made in molecular genetics has made it possible to categorise NPCA better, both their causation and their hereditary or sporadic nature remain unknown in about 50% of cases.

Les ataxies cérébelleuses autosomiques récessives avec apraxie oculomotrice

INTRODUCTION

Autosomal recessive cerebellar ataxias (ARCA) comprise a phenotypically and genetically heterogeneous group of diseases. Recently, a subgroup of ARCA associated with oculomotor apraxia has been delineated.

STATE OF THE ART

The ataxias with oculomotor apraxia (AOA) include four distinct genetic entities at least: ataxia-telangiectasia, ataxia telangiectasia-like disorder, ataxia with oculomotor apraxia type 1 (AOA1) and type 2 (AOA2). The responsible genes, ATM, MRE11, APTX and SETX respectively, are implicated in DNA-break repair mechanisms.

CONCLUSION

We describe the phenotypic and genetic characteristics of these ataxias, based on a review of the literature and a personal study of AOA1 and AOA2 patients.

[Autosomal recessive cerebellar ataxias. Their classification, genetic features and pathophysiology]

INTRODUCTION AND DEVELOPMENT

Autosomal recessive cerebellar ataxias (ARCA) are a heterogeneous group of rare neurological disorders involving both central and peripheral nervous system, and in some case other systems and organs. They use to have early onset before the age of 20. Based on pathogenic mechanisms five main types may be distinguished: congenital (developmental disorder), mitochondrial ataxias, ataxias associated with metabolic disorders, ataxias with a DNA repair defect, and degenerative ataxia with unknown pathogenesis. The most frequent in Caucasian population are Friedreich ataxia and ataxia-telangiectasia. Other forms are much less common, and include abetaliproteinemia, ataxia with vitamin E deficiency (AVED), ataxia with oculomotor apraxia types 1 (AOA1) and 2 (AOA2), early onset cerebellar ataxia with retained reflexes, Charlevoix-Saguenay spastic ataxia, and Joubert syndrome. The prevalence of ARCA has been estimated to 7 in 100,000 inhabitants. These diseases are due to mutations in specific genes, some of which and its encoded proteins have been identified, such as FRDA (frataxin) in Friedreich ataxia, APTX (aprataxin) in AOA1, alphaTTP (alpha-tocopherol transfer protein) in AVED, and STX (senataxin) in AOA2. Due to autosomal recessive inheritance, previous familial history of affected individuals unlikely.

CONCLUSIONS

Most of these cerebellar ataxias have no specific treatment with exception of the ataxia associated with deficiency coenzyme Q10 and abetalipoproteinemia. Clinical diagnosis must be confirmed by ancillary tests such as neuroimaging (magnetic resonance, scanning), electrophysiological examination, and mutation analysis when the causative gene has been identified. Correct clinical and genetic diagnosis is important for appropriate prognosis and genetic counseling and, in some instances, pharmacological treatment.

Treatment of cerebellar ataxia with 5‐HT1A agonist

Effective, pharmacologic approaches to the treatment of cerebellar ataxia are lacking or inadequate. We recently reported preliminary evidence that tandospirone citrate (tandospirone), a 5-HT1A agonist, improved cerebellar ataxia in patients with Machado-Joseph disease (MJD). In the course of that study, we found that such treatment also alleviated the pain associated with cold sensations in the legs, insomnia, anorexia, and depression, all of which are thought to be mediated through activation of the 5-HT1A receptor. In this paper, we reviewed the few published clinical trials that involved the use of 5-HT1A receptor agonists for the treatment of cerebellar ataxia, and discussed the current theories regarding their mechanism of action. Cortical cerebellar atrophy (CCA) was reported, in a double-blind study, to be amenable to treatment with tandospirone. Other types of spinocerebellar degeneration (SCD) i.e., olivopontocerebellar atrophy (OPCA) and Machado-Joseph disease (MJD) have also been reported to respond to the drug, but these have been small studies. Responsive patients exhibited only mild ataxia. The doses of 5-HT1A agonists that have been used successfully ranged from 12.5 mg/day to 60 mg/day (or 1 mg/kg), and were well tolerated by most patients.

Cerebellar/spinocerebellar syndromes

Spinocerebellar syndromes are a heterogeneous group of neurological disorders clinically characterized by dysequilibrium, progressive incoordination of gait and limbs, and speech and eye movement disturbances. Clinical classification and differential diagnosis are intricate due to the great variability of the phenotypic, pathogenic, neuropathological and genetic aspects of these diseases. Spinocerebellar syndromes may present as sporadic, nongenetic, disorders or as familial forms. Clinical and genetic classifications of autosomal dominant and recessive spinocerebellar ataxias are briefly reviewed. Distinguishing clinical features, diagnostic procedures, and frequency of specific genotypes in Italian patients are presented.

Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2

Familial hemiplegic migraine, episodic ataxia type 2 (EA2), and spinocerebellar ataxia type 6 are allelic disorders of the CACNA1A gene (coding for the alpha(1A) subunit of P/Q calcium channels), usually associated with different types of mutations (missense, protein truncating, and expansion, respectively). However, the finding of expansion and missense mutations in patients with EA2 has blurred this genotype-phenotype correlation. We report the first functional analysis of a new missense mutation, associated with an EA2 phenotype-that is, T-->C transition of nt 4747 in exon 28, predicted to change a highly conserved phenylalanine residue to a serine at codon 1491, located in the putative transmembrane segment S6 of domain III. Patch-clamp recording in HEK 293 cells, coexpressing the mutagenized human alpha(1A-2) subunit, together with human beta(4) and alpha(2)delta subunits, showed that channel activity was completely abolished, although the mutated protein is expressed in the cell. These results indicate that a complete loss of P/Q channel function is the mechanism underlying EA2, whether due to truncating or to missense mutations.

The inherited episodic ataxias: how well do we understand the disease mechanisms?

The past few years have seen the elucidation of several neurological diseases caused by inherited mutations of ion channels. In contrast to many other types of genetic disorders, the "channelopathies" can be studied with high precision by applying electrophysiological methods. This review evaluates the success of this approach in explaining the mechanisms of two forms of episodic ataxia that are known to be caused by mutations of ion channels: episodic ataxia type 1 (EA1, caused by K+ channel mutations) and episodic ataxia type 2 (EA2, caused by Ca2+ channel mutations). Although both of these disorders are rare, they raise many important questions about the roles of identified channels in brain function. Indeed, a resolution of the mechanisms by which both diseases occur will represent a major milestone in understanding diseases of the CNS, in addition to opening the way to novel possible treatments.

Genetic background of apparently idiopathic sporadic cerebellar ataxia

Disease-causing mutations have been identified in various entities of autosomal dominant ataxia and in Friedreich's ataxia. However, no molecular pathogenic factor is known to cause idiopathic cerebellar ataxias. We investigated the CAG/CTG trinucleotide repeats causing spinocerebellar ataxia types 1, 2, 3, 6, 7, 8 and 12, and the GAA repeat of the frataxin gene in 124 patients apparently suffering from idiopathic sporadic ataxia, including 20 patients with the clinical diagnosis of multiple system atrophy. Patients with a positive family history, a typical Friedreich phenotype, or symptomatic ataxia were excluded. Genetic analyses uncovered the most common Friedreich mutation in 10 patients with an age at onset between 13 and 36 years. The SCA6 mutation was present in nine patients with disease onset between 47 and 68 years of age. The CTG repeat associated with SCA8 was expanded in three patients. One patient had SCA2 attributable to a de novo mutation from a paternally transmitted, intermediate allele. We did not identify the SCA1, SCA3, SCA7 or SCA12 mutation in idiopathic sporadic ataxia patients. No trinucleotide repeat expansion was detected in the MSA subgroup. This study has revealed the genetic basis in 19% of apparently idiopathic ataxia patients. SCA6 is the most frequent mutation in late onset cerebellar ataxia. The frataxin trinucleotide expansion should be investigated in all sporadic ataxia patients with onset before age 40, even when the phenotype is atypical for Friedreich's ataxia.

Clinical and molecular advances in autosomal dominant cerebellar ataxias: from genotype to phenotype and physiopathology

Major advances have been made in the understanding of autosomal dominant cerebellar ataxias since genetic markers came into use in the 1980s. The subsequent mapping of nine genes, six of which have been identified, involved in this clinically diverse group of disorders highlighted their great genetic heterogeneity. Evidence is now accumulating that, except for SCA8, the same molecular and physiopathological processes underlie these diseases and other neurodegenerative disorders sharing the same mutational basis, the expansion of a (CAG)n-polyglutamine coding sequence. The clinical overlap among the different genetic entities makes prediction of the molecular origin impossible in a single patient so that molecular characterisation is necessary. However, extended clinical and neuropathological comparisons have shown that each genetic entity has a characteristic constellation of signs and symptoms that are related to CAG repeat size and disease duration. The combined genetic and clinical information form the basis of a new classification that will aid better understanding of disease evolution, assure follow up and permit genetic counselling by the clinician.

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.

Autosomal dominant cerebellar ataxia: phenotypic differences in genetically defined subtypes?

Seventy-seven families with autosomal dominant cerebellar ataxia were analyzed for the CAG repeat expansions causing spinocerebellar ataxia (SCA) types 1, 2, 3, and 6. The SCA1 mutation accounted for 9%, SCA2 for 10%, SCA3 for 42%, and SCA6 for 22% of German ataxia families. Seven of 27 SCA6 patients had no family history of ataxia. Age at onset correlated inversely with repeat length in all subtypes. Yet the average effect of one CAG unit on onset age was different for each SCA subtype. We compared clinical, electrophysiological, and magnetic resonance imaging (MRI) findings to identify phenotypic characteristics of genetically defined SCA subtypes. Slow saccades, hyporeflexia, myoclonus, and action tremor proposed SCA2. SCA3 patients frequently developed diplopia, severe spasticity or pronounced peripheral neuropathy, and impaired temperature discrimination, apart from ataxia. SCA6 presented with a predominantly cerebellar syndrome and patients often had onset after 55 years of age. SCA1 was characterized by markedly prolonged peripheral and central motor conduction times in motor evoked potentials. MRI scans showed pontine and cerebellar atrophy in SCA1 and SCA2. In SCA3, enlargement of the fourth ventricle was the main sequel of atrophy. SCA6 presented with pure cerebellar atrophy on MRI. However, overlap between the four SCA subtypes was broad.

[Familial periodic ataxia with myokymia sensitive to acetazolamide: a family case]

INTRODUCTION

Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia is a type of autosomal dominant cerebellar ataxia which locus was found to be linked to the short arm of chromosome 12 and the etiology is unknown.

CLINICAL CASE

A 12 years-old man who suffered from childhood daily episodes of sudden attacks sport induced with giddiness, ataxia and dysarthria for minutes. The familial history shows the same clinical findings in three generations. Intercritical general neurologic evaluation is otherwise normal. The following tests were performed with normal results: Biochemistry, electroencephalogram, cerebral magnetic resonance imaging. The electromyography showed myokymic discharges. The patient's symptoms improve on treatment with acetazolamide immediately.

CONCLUSIONS

Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia needs to think on it to be diagnosed. No typical complementary test (electromyography exception) induces to base diagnosis in the clinical findings, the familial history and the fast clinical improvement after starting treatment with acetazolamide.

Post-malarial cerebellar ataxia in adult Sudanese patients

In this study the clinical manifestation and the effect of corticosteroids on the course and the outcome of post malaria cerebellar ataxia on thirty adult Sudanese patients wr investigated. Twenty four patients with delayed ataxia, that is, ataxia occurring shortly after full recovery from otherwise uncomplicated, documented malaria and six patients who were found to be ataxic on recovery from cerebral malaria were included in the study. The distribution of the age, sex and various clinical aspects were outlined. Twelve randomly selected patients were given oral prednisolone. The corticosteroid was found to shorten the period of ataxia. It was also found that in patients who demonstrated cerebellar infarction or atrophy on computerised tomography the duration of ataxia was significantly long.

The prevalence and wide clinical spectrum of the spinocerebellar ataxia type 2 trinucleotide repeat in patients with autosomal dominant cerebellar ataxia

The dominant cerebellar ataxias (ADCAs) represent a clinically and genetically heterogeneous group of disorders linked by progressive deterioration in balance and coordination. The utility of genetic classification of the ADCAs has been highlighted by the striking variability in clinical phenotype observed within families and the overlap in clinical phenotype observed between those with different genotypes. The recent demonstration that spinocerebellar ataxia type 2 (SCA2) is caused by a CAG repeat expansion within the ataxin-2 gene has allowed us to determine the frequency of SCA2 compared with SCA1, SCA3/Machado-Joseph disease (MJD), and dentatorubropallidoluysian atrophy (DRPLA) in patients with sporadic and inherited ataxia. SCA2 accounts for 13% of patients with ADCA (without retinal degeneration), intermediate between SCA1 and SCA3/MJD, which account for 6% and 23%, respectively. Together, SCA1, SCA2, and SCA3/MJD constitute >40% of the mutations leading to ADCA I in our population. No patient without a family history of ataxia, or with a pure cerebellar or spastic syndrome, tested positive for SCA1, SCA2, or SCA3. No overlap in ataxin-2 allele size between normal and disease chromosomes, or intermediate-sized alleles, were observed. Repeat length correlated inversely with age at onset, accounting for approximately 80% of the variability in onset age. Haplotype analysis provided no evidence for a single founder chromosome, and diverse ethnic origins were observed among SCA2 kindreds. In addition, a wide spectrum of clinical phenotypes was observed among SCA2 patients, including typical mild dominant ataxia, the MJD phenotype with facial fasciculations and lid retraction, and early-onset ataxia with a rapid course, chorea, and dementia.

Refinement by linkage analysis in two large families of the candidate region of the third locus (SCA3) for autosomal dominant cerebellar ataxia type I

The autosomal dominant cerebellar ataxias (ADCA) are clinically and genetically heterogeneous. To date, several loci (SCAI-V) have been identified for ADCA type I. We have studied two large families from the northern part of The Netherlands with ADCA type I with a broad intra-familial variation of symptoms. In both families significant linkage is shown of the disease to the markers of the SCA3 locus on chromosome 14. Through recombinations, the candidate region for SCA3 could be refined to a 13-cM range between D14S256 and D14S81. No recombinations were detected with the markers D14S291 and D14S280, which suggests that the SCA3 gene lies close to these loci. This finding will benefit the individuals at risk in these two families who are seeking predictive testing or prenatal diagnosis.

Localization of autosomal dominant cerebellar ataxia associated with retinal degeneration and anticipation to chromosome 3p12-p21.1

We present linkage analysis on a large Swedish five-generation family of 15 affected individuals with autosomal dominant cerebellar ataxia (ADCA) associated with retinal degeneration and anticipation. Common clinical signs in this family include ataxia, dysarthria and severely impaired vision with the phenotype ADCA type II. Different subtypes of ADCA have proven difficult to classify clinically due to extensive phenotypic variability within and between families. Genetic analysis of a number of ADCA type I families shows that heterogeneity exists also genetically. During the last few years several types of ADCA type I have been localized and to date six genetically distinct forms have been identified including SCA1 (6p), SCA2 (12q), SCA3 and Machado-Joseph disease (MJD) (14q), SCA4 (16q), and finally SCA5 (11). We performed a genome-wide search of the Swedish ADCA type II family using a total of 270 microsatellite markers. Positive lod scores were obtained with a number of microsatellite markers located on chromosome 3p12-p21.1. Three markers gave lod scores over 3 with a maximum lod score of 4.53 achieved with the marker D3S1600. The ADCA type II gene could be restricted to a region of 32 cM by the markers D3S1547 and D3S1274.

Familial periodic cerebellar ataxia without myokymia maps to a 19-cM region on 19p13

Familial periodic cerebellar ataxia (FPCA) is a heterogeneous group of rare autosomal dominant disorders characterized by episodic cerebellar disturbance. A potassium-channel gene (KCNA1) has been found to be responsible for one of its subgroups, familial periodic cerebellar ataxia with myokymia (FPCA/+M; MIM 160120). A different subgroup that is not associated with myokymia (FPCA/-M; MIM 108500) was recently mapped to chromosome 19p. Here we have performed linkage analysis in two large families with FPCA/-M that also demonstrated neurodegenerative pathology of the cerebellum. Three markers in 19p13 gave significant lod scores (> 3.0), while linkage to KCNA1 and three known loci for spinocerebellar ataxia (SCA1, SCA2, and SCA3) was excluded. The highest lod score was obtained with the marker D19S413 (4.4 at recombination fraction 0), and identification of meiotic recombinants in affected individuals placed the locus between the flanking markers D19S406 and D19S226, narrowing the interval to 19 cM. A CAG trinucleotide-repeat expansion was detected in one family but did not cosegregate with the disease.

Re-examining the concept of severity in traumatic brain injury

This paper re-examines the theoretical concept of severe brain injury focusing on the duration of coma as a precise indicator of the clinical profile. A retrospective hospital chart study of 361 traumatic brain-injured patients was undertaken to determine the homogeneity of the subsample of the severely brain-injured (defined as 2 or more days of coma) with respect to the probability of four types of impairment: ataxia, contractures, paralysis and speech impairment. The current concept of severity assumes homogeneity among the 'severely brain-injured'. However, our results indicate significant differences in impairment within this population. The authors feel strongly that future studies must describe coma duration in finer gradations, and test for homogeneity within samples before inferences are made. Improvements in life-sustaining technologies have resulted in longer coma durations. The need to use coma days as an indicator of impairment rather than a broad category of severity is emphasized.

Autosomal-dominant cerebellar ataxia with retinal degeneration (ADCA type II) is genetically different from ADCA type I

Autosomal-dominant cerebellar ataxia (ADCA) type II is a neurodegenerative disorder presenting with cerebellar ataxia and retinal degeneration. We analyzed the clinical features of 21 patients with ADCA type II from 3 Moroccan and 2 French families. Mean age at onset was 17 years earlier in offspring than in their parents, compatible with anticipation. There was a suggestion of imprinting, with predominantly paternal transmission of early onset and severe forms of the affection. Candidate genes were tested in the family with the largest pedigree. The two known loci for ADCA type I (spinal cerebellar ataxia 1 and 2) were excluded, as were candidate loci, retinitis pigmentosa 1 locus (RP1) and the genes for rhodopsin and peripherin-rds, responsible for autosomal dominant retinitis pigmentosa. ADCA type II does not therefore result from an allelic mutation of the tested genes for ADCA type I or autosomal dominant retinitis pigmentosa.

Molecular heterogeneity of autosomal dominant cerebellar ataxia: analysis of flanking microsatellites of the spinocerebellar ataxia 1 locus in a northern European family unequivocally demonstrates non-linkage

This study addresses the question whether the different forms of autosomal dominant cerebellar ataxia (ADCA) are related to different ethnic/geographical regions in Europe. One mutation in families originating from Holland, Prussia and Italy has previously been localized to chromosome 6p (SCA1 locus), whereas the mutation in families of Iberic origin has been excluded from chromosome 6p. In a Danish five-generation pedigree with ADCA and in which previous HLA-serotyping had shown inconclusive linkage results, the present study shows unequivocal exclusion from the SCA1 locus, firstly through the use of the new, highly informative microsatellites D6S89 and D6S109, which closely flank the SCA1 locus, and secondly through the manifestation of disease in four pedigree members previously scored as unaffected. Additional molecular genetic analysis of the HLA DRbeta and F13A polymorphisms also argue against a cluster of ADCA genes on chromosome 6p. Since this study demonstrates the existence of non-SCA1 families and therefore heterogeneity in the North-European population, molecular family counselling remains restricted to the few known SCA1 families.

Classifications of hereditary ataxias. A critical overview

The classifications of hereditary ataxias (HA) proposed from 1907 to 1984 are reviewed. An analysis is provided of the possible variables in the classification of HA, including inheritance, known metabolic or other cause, localization of pathological lesions, clinical signs, natural history, epidemiology, diagnostic tools. Harding's classification is assumed to be the best clinical tool to support molecular genetics studies. However, we suggest the inclusion of Late Onset Recessive Cerebellar Ataxias in Harding's classification. Some exceptions must be considered for the diagnostic criteria of Friedreich's disease. Early Onset Cerebellar Ataxia with retained tendon reflexes (EOCA) is probably a heterogeneous entity.

[Classification of hereditary cerebellar ataxias]

The hereditary cerebellar ataxias are one of the most complex group of neurogenetic diseases. A review of the several attempts do classify the heredoataxias is presented. The classifications based on clinical and genetic grounds are the most useful. The recent advances in molecular genetics are prone to give important clues for elucidation and understanding of the pathogenesis of heredodegenerative cerebellar diseases.

Cone dysfunction in a subgroup of patients with autosomal dominant cerebellar ataxia

Four patients with autosomal dominant cerebellar ataxia and retinal degeneration underwent neurologic and ophthalmologic examinations and computer-assessed corneal electroretinography. Previous reports described progressive panretinal degeneration initially involving the cones and subsequently spreading to the rods. By contrast, all our patients displayed evidence of selective dysfunction of the cone system in one or two successive electroretinograms, irrespective of their age or duration of visual symptoms. Color vision testing, funduscopy, and fluorescein angiography suggested a cone dystrophy. Within the period of observation only one patient showed progression of cone dysfunction. In patients with hereditary ataxias, quantitative electroretinography provides an objective and sometimes early indication of retinal degeneration and helps to characterize it.

Utility of short-latency evoked potentials in the classification of progressive, early onset cerebellar ataxias

In recent years, several authors have proposed new classifications of inherited ataxias, some of them being based on systematic clinical studies of large groups of patients. This methodic approach has led to the identification of new types of ataxias and helped the development of molecular biology research in these diseases. Up to now, nerve conduction velocity and evoked potential studies have not been considered in the classification of hereditary ataxias. We have studied the results of short latency evoked potentials in 102 patients affected by a early onset, progressive cerebellar ataxia. Based on the results of this study and a review of the literature on this subject, we will evaluate the utility of nerve conduction velocity and evoked potential recordings in the classification of this group of diseases.

[A nosological study of a patient showing ataxia & lower motor neuron involvement]

A sporadic case of spinocerebellar degeneration with prominent involvement of the motor system has recently been encountered. A 54-year-old man without family history noticed speech disturbance at the age of 46 and weakness in his right hand the following year. The muscle weakness and atrophy were slowly progressive and made walk impossible at the age of 50, when his dysphagia increased. At the age of 54, he was admitted to our hospital when neurological findings revealed marked amyotrophy of general skeletal muscle and tongue with fasciculation. Deep tendon reflexes were decreased. Cerebellar ataxia was impossible to evaluate because of profound muscle weakness. And sensory disturbance was suspected in the distal portion of the lower extremities. CT scan revealed progressive atrophy of the brain stem and cerebellum. The patient died at the age of 54 due to CO2 narcosis. The clinical course was 8 years. A summary of the pathological findings was as follows: 1) Marked neuronal loss of the anterior horn of the spinal cord and motor cranial nerve nuclei except for oculomotor nuclei, with mild degeneration of pyramidal tract below lumbosacral level. 2) Degeneration of cerebellipetal system, spinocerebellar tract, Clarke's column and the middle root zone and cerebellifugal system, dentate nucleus, superior cerebellar peduncles, and red nucleus. 3) Mild degeneration of pontine nuclei, inferior olivary nuclei, pontine transverse fibers, the middle and inferior cerebellar peduncles, cerebellar white matter and Purkinje cells as in OPCA.(ABSTRACT TRUNCATED AT 250 WORDS)

[Computerized tomography in the study of degenerative ataxia]

We describe the computerized tomography findings in 85 patients affected with degenerative ataxias. Cerebellar atrophy was moderate in patients with Friedreich's disease (no. 28) and early onset cerebellar ataxia with retained reflexes (no. 10) and, in Friedreich's disease, it was mostly a late feature. On the contrary, in symptomatic patients with adult onset dominant cerebellar ataxia (no. 24), cerebellar atrophy was always present and often marked. However, it was absent in 3 asymptomatic affected relatives. Infratentorial and supratentorial atrophy were frequent findings in idiopathic late onset cerebellar ataxia (no. 16).

The nosological position of the ophthalmoplegia, ataxia and areflexia syndrome: "the spectrum hypothesis"

Two cases of ophthalmoplegia ataxia and areflexia are described, each with undoubted central and peripheral neural affection. It is concluded that the cardinal features are due to brainstem pathology, and support the hypothesis that this syndrome and the post-infectious polyradiculoneuritides represent differing ends of a spectrum which reflects two modes of nervous system reaction to a presumed infective challenge.

A clinical classification of hereditary ataxias

We present a working and flexible classification of inherited ataxic syndromes based on the use of simple tools available to every clinician: a good history (particularly pinpointing the age of onset, the rate of progression and the mode of inheritance) and a neurological examination (identifying the presence of ataxia, deep tendon reflexes in the knee, optic nerve, retinal and/or 8th nerve signs). This classification is easily coded for computer translation on any personal computer. The place occupied by a given disorder may, by contiguity, give a clue to its pathophysiology.

[The nosology of cerebellar ataxias]

The group of cerebellar ataxias in adults represents a collection of very heterogeneous causes, pathogeneses, morphological changes and - as far as the hereditary types are concerned - heredity. Different modes of inheritance (dominant or recessive) signify different aetiologies to the geneticist. However, genetic heterogeneity is often associated with similarities of the phenotypes concerned. A decisive descriptive differentiation is that between a) degenerative changes of the cerebellum and the pertaining paths and b) cerebellar ataxias with associated non-neural changes. Meanwhile consensus has been reached regarding the gross anatomical classification of cerebellar ataxias into a) olivopontocerebellar atrophies ("cerebellopetal") b) primary cerebellar parenchymatrophies ("cerebellofugal"). A more reliable classification of the monogenic types will become possible in the near future with the help of the genetic marker of the HLA haplotypes. A comprehensive classification of non-hereditary and hereditary cerebellar ataxias based on clinical, pathologico-anatomical and genetic parameters is presented and summarized in Table 4.

Genetic and clinical patterns of heritable cerebellar ataxias in adults. I. Genetic analyses

Family data on 299 probands with spinocerebellar types, 163 with late cortical cerebellar atrophies (LCCA), and 180 with olivopontocerebellar atrophies (OPCA) were analysed. Spinocerebellar types included cases with cerebellar ataxia combined with spasticity. Their family history was not compatible with sex linked inheritance. There were few recessive cases occurring before 24 years of age. The majority of cases were products of non-consanguineous marriages in which one partner was affected. The genetic ratio was 0.5 for each decade at onset between 20 and 59, suggesting that these cases were dominant. The proportion of these familial cases, however, decreased with increasing age at onset, and there were quite a few sporadic cases among the elderly. LCCA and OPCA were considered to represent extremes of a correlated disease spectrum. Although they were weakly familial, single gene heredity was rejected. Sib recurrence rate was 7.5% for LCCA and 9.4% for OPCA. When calculated for different age groups at onset, the rates decreased with increasing age in the two diseases. The rates increased to 25% and 20%, respectively, given two sibs already affected, and to 37.5% and 22.2% when three were affected. These patterns were incompatible with single gene mechanisms and were similar to those in multifactorial diseases with a threshold effect.

Linkage studies in spinocerebellar ataxia (SCA)

Data are now available on 9 pedigrees in detail and 4 pedigrees as lod scores only. Linkage to HLA is significant (Z = 5.53 at recombination rates of 0.223 in males and 0.327 in females). Tight linkage is excluded. Nine pedigrees which appear to be typical olivopontocerebellar atrophy (OPCA I) have recombination rates of 0.150 in males and 0.300 in females. The remaining 4 pedigrees are clinically atypical or include discrepant data and give no evidence for linkage. The symbol SCA1 is proposed for a locus on chromosome 6 (loosely linked to HLA), at which at least one allele produces OPCA I (Menzel type). It is not yet clear whether other clinical types are determined by alleles at different loci, although this is suggested by several pedigrees, including a Danish pedigree of OPCA with dementia. Linkage evidence will be decisive in delineating the ataxias.