scholarly journals Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS): from clinical diagnosis towards genetic testing

2021 ◽  
Vol 33 (4) ◽  
pp. 301-310
Author(s):  
Andreas Thieme ◽  
Christel Depienne ◽  
Dagmar Timmann
Keyword(s):  
Cerebellar Ataxia ◽  
Chronic Cough ◽  
Late Onset ◽  
Neurological Diseases ◽  
Brain Mri ◽  
Genetic Research ◽  
Sensory Nerve ◽  
Repeat Expansions ◽  
Factor C ◽  
Pentanucleotide Repeat

Abstract The cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a late-onset and recessively inherited ataxia. For many years, CANVAS has been diagnosed based on the clinical phenotype. Only recently, a large biallelic pentanucleotide repeat expansion in the replication factor C subunit 1 (RFC1) gene has been identified as the underlying genetic cause for the large majority of CANVAS cases. Subsequently, other phenotypes such as ataxia with chronic cough, incomplete CANVAS and MSA-C-like phenotypes have been associated with biallelic RFC1 repeat expansions. Because of this heterogeneity it has been suggested to change the name of the disease to “RFC1 disease”. Chronic cough is characteristic and can precede neurological symptoms by years or decades. In the neurological examination signs of cerebellar, sensory, and vestibular ataxia are frequently observed. Nerve conduction studies usually show absent or markedly reduced sensory nerve action potentials. On brain MRI cerebellar degeneration and spinal cord alterations are common. In later disease stages more widespread neurodegeneration with additional involvement of the brainstem and basal ganglia is possible. As yet, the exact incidence of RFC1-associated neurological diseases remains uncertain although first studies suggest that RFC1-related ataxia is common. Moreover, the pathophysiological mechanisms caused by the large biallelic pentanucleotide repeat expansions in RFC1 remain elusive. Future molecular and genetic research as well as natural history studies are highly desirable to pave the way towards personalized treatment approaches.

Clinical spectrum of the pentanucleotide repeat expansion in the RFC1 gene in ataxia syndromes

Neurology ◽  
2020 ◽  
Vol 95 (21) ◽  
pp. e2912-e2923
Author(s):  
Maria Gisatulin ◽  
Valerija Dobricic ◽  
Christine Zühlke ◽  
Yorck Hellenbroich ◽  
Vera Tadic ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Late Onset ◽  
Intron Retention ◽  
Repeat Expansion ◽  
Healthy Controls ◽  
Neighboring Gene ◽  
Number Of Patients ◽  
C Subunit ◽  
Factor C ◽  
Pentanucleotide Repeat

ObjectiveTo determine the clinical significance of an intronic biallelic pentanucleotide repeat expansion in the gene encoding replication factor C subunit 1 (RFC1) in patients with late-onset cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), in patients with other ataxias, and in healthy controls by comprehensive genetic analyses.MethodsIn this case-control study, we included 457 individuals comprising 26 patients with complete or incomplete CANVAS, 70 patients with late-onset cerebellar ataxia, 208 healthy controls, and 153 individuals from 39 multigenerational families without ataxia to determine repeat stability. All 96 patients were screened for the repeat expansion by duplex PCR. To further characterize the repeat type and lengths, we used fragment length analysis, repeat-primed PCR, Sanger sequencing, and Southern blotting. Expression of RFC1 and the neighboring gene WDR19 were determined by quantitative PCR.ResultsMassive biallelic pentanucleotide expansions were found in 15/17 patients with complete CANVAS (88%), in 2/9 patients with incomplete CANVAS (22%), in 4/70 patients with unspecified, late-onset cerebellar ataxia (6%), but not in controls. In patients, the expansion comprised 800–1,000 mostly AAGGG repeats. Nonmassively expanded repeat numbers were in the range of 7–137 repeats and relatively stable during transmission. Expression of RFC1 and WDR19 were unchanged and RFC1 intron retention was not found.ConclusionsA biallelic pentanucleotide repeat expansion is a frequent cause of CANVAS and found in a considerable number of patients with an incomplete clinical presentation or other forms of cerebellar ataxia. The mechanism by which the repeat expansions are causing disease remains unclear and warrants further investigations.

scholarly journals Cerebellar ataxia, neuropathy, vestibular areflexia syndrome due to RFC1 repeat expansion

Brain ◽  
2020 ◽  
Vol 143 (2) ◽  
pp. 480-490 ◽  
Author(s):  
Andrea Cortese ◽  
Stefano Tozza ◽  
Wai Yan Yau ◽  
Salvatore Rossi ◽  
Sarah J Beecroft ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Late Onset ◽  
Sensory Neuropathy ◽  
Repeat Expansion ◽  
Cerebellar Dysfunction ◽  
Full Spectrum ◽  
Ataxic Neuropathy ◽  
Walking Aids ◽  
Repeat Expansions ◽  
Walking Difficulty

Abstract Ataxia, causing imbalance, dizziness and falls, is a leading cause of neurological disability. We have recently identified a biallelic intronic AAGGG repeat expansion in replication factor complex subunit 1 (RFC1) as the cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) and a major cause of late onset ataxia. Here we describe the full spectrum of the disease phenotype in our first 100 genetically confirmed carriers of biallelic repeat expansions in RFC1 and identify the sensory neuropathy as a common feature in all cases to date. All patients were Caucasian and half were sporadic. Patients typically reported progressive unsteadiness starting in the sixth decade. A dry spasmodic cough was also frequently associated and often preceded by decades the onset of walking difficulty. Sensory symptoms, oscillopsia, dysautonomia and dysarthria were also variably associated. The disease seems to follow a pattern of spatial progression from the early involvement of sensory neurons, to the later appearance of vestibular and cerebellar dysfunction. Half of the patients needed walking aids after 10 years of disease duration and a quarter were wheelchair dependent after 15 years. Overall, two-thirds of cases had full CANVAS. Sensory neuropathy was the only manifestation in 15 patients. Sixteen patients additionally showed cerebellar involvement, and six showed vestibular involvement. The disease is very likely to be underdiagnosed. Repeat expansion in RFC1 should be considered in all cases of sensory ataxic neuropathy, particularly, but not only, if cerebellar dysfunction, vestibular involvement and cough coexist.

scholarly journals CANVAS: a late onset ataxia due to biallelic intronic AAGGG expansions

2020 ◽  
Author(s):  
Natalia Dominik ◽  
Valentina Galassi Deforie ◽  
Andrea Cortese ◽  
Henry Houlden
Keyword(s):  
Late Onset ◽  
Replication Factor C ◽  
Common Cause ◽  
Progressive Ataxia ◽  
The World ◽  
Recent Developments ◽  
C Subunit ◽  
Repeat Expansions ◽  
Visual Problems ◽  
Factor C

Abstract The ataxias are a group of disorders that manifest with balance, movement, speech and visual problems. They can arise due to dysfunction of the cerebellum, the vestibular system and/or the sensory neurons. Genetic defects are a common cause of chronic ataxia, particularly common are repeat expansions in this group of conditions. Co-occurrence of cerebellar ataxia with neuropathy and vestibular areflexia syndrome has been termed CANVAS. Although CANVAS is a rare syndrome, on discovery of biallelic expansions in the second intron of replication factor C subunit 1 (RFC1) gene, we and others have found the phenotype is broad and RFC1 expansions are a common cause of late-onset progressive ataxia. We aim to provide a review and update on recent developments in CANVAS and populations, where the disorder has been reported. We have also optimised a protocol for RFC1 expansion screening which is described herein and expanded phenotype after analysing late-onset ataxia patients from around the world.

scholarly journals Update on Cerebellar Ataxia with Neuropathy and Bilateral Vestibular Areflexia Syndrome (CANVAS)

2020 ◽  
Author(s):  
Mathieu Dupré ◽  
Ruben Hermann ◽  
Caroline Froment Tilikete
Keyword(s):  
Cerebellar Ataxia ◽  
Late Onset ◽  
Genetic Disorder ◽  
Axonal Neuropathy ◽  
Sensory Neuropathy ◽  
Bilateral Vestibulopathy ◽  
Familial Form ◽  
Vestibulo Ocular Reflex ◽  
Classical Triad ◽  
Factor C

Abstract The syndrome of cerebellar ataxia with neuropathy and bilateral vestibular areflexia (CANVAS) has emerged progressively during the last 30 years. It was first outlined by the neurootology/neurophysiology community in the vestibular areflexic patients, through the description of patients slowly developing late-onset cerebellar ataxia and bilateral vestibulopathy. The characteristic deficit of visuo-vestibulo-ocular reflex (VVOR) due to the impaired slow stabilizing eye movements was put forward and a specific disease subtending this syndrome was suggested. The association to a peripheral sensory axonal neuropathy was described later on, with neuropathological studies demonstrating that both sensory neuropathy and vestibular areflexia were diffuse ganglionopathy. Clinical and electrophysiological criteria of CANVAS were then proposed in 2016. Besides the classical triad, frequent chronic cough, signs of dysautonomia and neurogenic pains were frequently observed. From the beginning of published cohorts, sporadic as well as familial cases were reported, the last suggestive of an autosomal recessive mode of transmission. The genetic disorder was discovered in 2019, under the form of abnormal biallelic expansion in the replication factor C subunit 1 (RFC1) in a population of late-onset ataxia. This pathological expansion was found in 100% of the familial form and 92% of sporadic ones when the triad was complete. But using the genetic criteria, the phenotype of CANVAS seems to expand, for exemple including patients with isolated neuronopathy. We propose here to review the clinical, electrophysiological, anatomical, genetic aspect of CANVAS in light of the recent discovery of the genetic aetiology, and discuss differential diagnosis, neuropathology and physiopathology.

Biallelic RFC1 pentanucleotide repeat expansions in Greek patients with late‐onset ataxia

2021 ◽  
Author(s):  
Zoi Kontogeorgiou ◽  
Chrisoula Kartanou ◽  
Chrysanthi Tsirligkani ◽  
Evangelos Anagnostou ◽  
Michail Rentzos ◽  
...  
Keyword(s):  
Late Onset ◽  
Repeat Expansions ◽  
Pentanucleotide Repeat

scholarly journals Prevalence of RFC1-mediated spinocerebellar ataxia in a North American ataxia cohort

2020 ◽  
Vol 6 (3) ◽  
pp. e440 ◽  
Author(s):  
Dona Aboud Syriani ◽  
Darice Wong ◽  
Sameer Andani ◽  
Claudio M. De Gusmao ◽  
Yuanming Mao ◽  
...  
Keyword(s):  
North America ◽  
Cerebellar Ataxia ◽  
Spinocerebellar Ataxia ◽  
Adaptor Protein ◽  
Spinocerebellar Ataxia Type ◽  
Initial Cohort ◽  
C Subunit ◽  
Heterozygous Sample ◽  
Repeat Expansions ◽  
Factor C

ObjectiveWe evaluated the prevalence of pathogenic repeat expansions in replication factor C subunit 1 (RFC1) and disabled adaptor protein 1 (DAB1) in an undiagnosed ataxia cohort from North America.MethodsA cohort of 596 predominantly adult-onset patients with undiagnosed familial or sporadic cerebellar ataxia was evaluated at a tertiary referral ataxia center and excluded for common genetic causes of cerebellar ataxia. Patients were then screened for the presence of pathogenic repeat expansions in RFC1 (AAGGG) and DAB1 (ATTTC) using fluorescent repeat-primed PCR (RP-PCR). Two additional undiagnosed ataxia cohorts from different centers, totaling 302 and 13 patients, respectively, were subsequently screened for RFC1, resulting in a combined 911 subjects tested.ResultsIn the initial cohort, 41 samples were identified with 1 expanded allele in the RFC1 gene (6.9%), and 9 had 2 expanded alleles (1.5%). For the additional cohorts, we found 20 heterozygous samples (6.6%) and 17 biallelic samples (5.6%) in the larger cohort and 1 heterozygous sample (7.7%) and 3 biallelic samples (23%) in the second. In total, 29 patients were identified with biallelic repeat expansions in RFC1 (3.2%). Of these 29 patients, 8 (28%) had a clinical diagnosis of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), 14 had cerebellar ataxia with neuropathy (48%), 4 had pure cerebellar ataxia (14%), and 3 had spinocerebellar ataxia (10%). No patients were identified with expansions in the DAB1 gene (spinocerebellar ataxia type 37).ConclusionsIn a large undiagnosed ataxia cohort from North America, biallelic pathogenic repeat expansion in RFC1 was observed in 3.2%. Testing should be strongly considered in patients with ataxia, especially those with CANVAS or neuropathy.

scholarly journals Idiopathic very late-onset cerebellar ataxia: a Brazilian case series

2015 ◽  
Vol 73 (11) ◽  
pp. 903-905 ◽  
Author(s):  
Hélio A. G. Teive ◽  
Mariana Moscovich ◽  
Adriana Moro ◽  
Marina Farah ◽  
Walter O. Arruda ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Visual Loss ◽  
Age Of Onset ◽  
Late Onset ◽  
Brain Mri ◽  
Cerebellar Atrophy ◽  
Case Series ◽  
Gait Ataxia ◽  
The One ◽  
Brazilian Case

ABSTRACTThe authors present a Brazilian case series of eight patients with idiopathic very-late onset (mean 75.5 years old) cerebellar ataxia, featuring predominantly gait ataxia, associated with cerebellar atrophy.Method: 26 adult patients with a diagnosis of idiopathic late onset cerebellar ataxia were analyzed in a Brazilian ataxia outpatient clinic and followed regularly over 20 years. Among them, 8 elderly patients were diagnosed as probable very late onset cerebellar ataxia. These patients were evaluated with neurological, ophthalmologic and Mini-Mental Status examinations, brain MRI, and EMG.Results: 62.5% of patients were males, mean age was 81.9 years-old, and mean age of onset was 75.5 years. Gait cerebellar ataxia was observed in all patients, as well as, cerebellar atrophy on brain MRI. Mild cognitive impairment and visual loss, due to macular degeneration, were observed in 50% of cases. Chorea was concomitantly found in 3 patients.Conclusion: We believe that this condition is similar the one described by Marie-Foix-Alajouanine presenting with mild dysarthria, associated with gait ataxia, and some patients had cognitive dysfunction and chorea.

CANVAS is a common form of late-onset hereditary ataxia

2020 ◽  
pp. 51-52
Author(s):  
Е.П. Нужный ◽  
Н.Ю. Абрамычева ◽  
Е.Г. Воробьева ◽  
Е.О. Иванова ◽  
Ю.А. Шпилюкова ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Clinical Picture ◽  
Autosomal Recessive ◽  
Late Onset ◽  
Repeat Expansion ◽  
Hereditary Ataxia ◽  
Recessive Ataxia ◽  
Autosomal Recessive Ataxia

Синдром CANVAS (мозжечковая атаксия, невропатия и вестибулярная арефлексия) - аутосомно-рецессивная атаксия с поздним дебютом, обусловленная носительством биаллельной экспансии (AAGGG)n во 2-м интроне гена RFC1. До настоящего момента отсутствуют сведения о распространенности данного заболевания в российских семьях. Нами был проведен поиск биаллельной экспансии AAGGG-повторов у 35 российских пациентов с поздней мозжечковой атаксией. Верифицированы 5 пациентов (14,3%) с синдромом CANVAS и характерной клинической картиной. CANVAS (cerebellar ataxia, neuropathy and vestibular areflexia) is a late-onset autosomal recessive ataxia due to biallelic (AAGGG)n repeat expansion in the 2nd intron of the RFC1 gene. There is no information on the CANVAS prevalence in Russian families. We searched for biallelic expansion of AAGGG repeats in 35 Russian patients with late-onset cerebellar ataxia. Five patients (14.3%) with CANVAS syndrome and a characteristic clinical picture were verified.

Late-onset cerebellar ataxia due to Gordon Holmes Syndrome

2020 ◽  
Vol 79 ◽  
pp. e113-e114
Author(s):  
C.-Y. Kok ◽  
T.-Y. Tee ◽  
A. Karim ◽  
H. Leong
Keyword(s):  
Cerebellar Ataxia ◽  
Late Onset

scholarly journals REscan: inferring repeat expansions and structural variation in paired-end short read sequencing data

2020 ◽  
Author(s):  
Russell Lewis McLaughlin
Keyword(s):  
Structural Variation ◽  
Sequence Data ◽  
Neurological Diseases ◽  
Repeat Expansion ◽  
Sequencing Data ◽  
Short Read ◽  
Short Read Sequencing ◽  
Repeat Expansions ◽  
Paired End Sequencing

Abstract Motivation Repeat expansions are an important class of genetic variation in neurological diseases. However, the identification of novel repeat expansions using conventional sequencing methods is a challenge due to their typical lengths relative to short sequence reads and difficulty in producing accurate and unique alignments for repetitive sequence. However, this latter property can be harnessed in paired-end sequencing data to infer the possible locations of repeat expansions and other structural variation. Results This article presents REscan, a command-line utility that infers repeat expansion loci from paired-end short read sequencing data by reporting the proportion of reads orientated towards a locus that do not have an adequately mapped mate. A high REscan statistic relative to a population of data suggests a repeat expansion locus for experimental follow-up. This approach is validated using genome sequence data for 259 cases of amyotrophic lateral sclerosis, of which 24 are positive for a large repeat expansion in C9orf72, showing that REscan statistics readily discriminate repeat expansion carriers from non-carriers. Availabilityand implementation C source code at https://github.com/rlmcl/rescan (GNU General Public Licence v3).

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