Disease Profile

Spastic ataxia Charlevoix-Saguenay type

Prevalence ?
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of Onset

Infancy

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ICD-10

G11.1

Inheritance

Autosomal dominant ?A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive ?Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked dominant ?X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked recessive ?Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic ?Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor ?Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other Names (AKA)

SACS; Charlevoix-Saguenay spastic ataxia; Autosomal recessive spastic ataxia of Charlevoix-Saguenay;

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
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Orpha Number: 98

Definition
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a neurodegenerative disorder characterised by early-onset cerebellar ataxia with spasticity, a pyramidal syndrome and peripheral neuropathy.

Epidemiology
It was initially described in the Charlevoix-Saguenay region of Quebec where incidence of ARSACS at birth has been estimated at 1 in 1,932. The incidence and prevalence worldwide remain unknown but ARSACS is very rare in other countries with cases described from Turkey, Japan, The Netherlands, Italy, Belgium, France and Spain.

Clinical description
The age of onset in non-Quebec patients is variable (ranging from late infantile, juvenile to early-adult onset) but in individuals from Quebec, onset occurs between 12 and 18 months of age with gait disturbance and walking difficulties. Other early signs of cerebellar ataxia include dysarthria and nystagmus. The spasticity is progressive and eventually dominates the clinical picture. The pyramidal syndrome is characterised by brisk patellar tendon reflexes and the Babinski sign. Onset of the peripheral neuropathy generally occurs later and leads to absence of the Achilles tendon reflex, distal amyotrophy and deep sensory disturbances (impaired vibration sense). Retinal hypermyelination (without vision loss) is a constant feature in ARSACS patients from Quebec but may be absent in patients from other countries. Lack of leg spasticity has been reported in some Japanese families and intellectual deficit may be a feature in some non-Quebec patients. Other manifestations may include mitral valve prolapse, pes cavus, and bladder dysfunction.

Etiology
ARSACS is caused by autosomal recessive mutations in the SACS gene (13q11), which encodes a large protein of unknown function named sacsin.

Diagnostic methods
Clinical diagnosis relies on the results of neuroimaging studies (MRI and CT scans revealing atrophy of the upper cerebellar vermis and cervical spinal cord) and neurophysiological data (signs of both axonal and demyelinating neuropathy, with nerve conduction studies revealing loss of sensory nerve conduction and reduced motor conduction velocities). Retinal examination may also be useful for diagnosis. Diagnosis can be confirmed by detection of SACS mutations.

Differential diagnosis
Differential diagnoses include other autosomal recessive ataxias, such as Friedreich ataxia and ataxia with vitamin E deficiency (AVED), and hereditary forms of spastic paraplegia (see these terms), in particular spastic paraplegia 20 (SPG20-Troyer syndrome).

Antenatal diagnosis
Prenatal diagnosis is possible when the disease-causing mutation has been identified and genetic counselling should be offered to affected families.

Management and treatment
Treatment is symptomatic aiming towards controlling the spasticity and should include physiotherapy, pharmacotherapy and use of ankle-foot orthoses.

Prognosis
Most patients become wheelchair-bound by the 5th decade of life. Death generally occurs during the sixth decade but survival into the seventies has been reported.

Visit the Orphanet disease page for more resources.

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Abnormal motor evoked potentials
0012896
Abnormality of the cerebellar peduncle
0011931
Abnormality of the pons
0007361
Arachnoid cyst
Fluid-filled sac located in membrane surrounding brain or spinal cord
0100702
Babinski sign
0003487
Cerebellar atrophy
Degeneration of cerebellum
0001272
Cerebellar vermis hypoplasia
0001320
Demyelinating peripheral neuropathy
0007108
Difficulty walking
Difficulty in walking
0002355
Dysarthria
Difficulty articulating speech
0001260
Dysmetria
Lack of coordination of movement
0001310
Gaze-evoked horizontal nystagmus
0007979
Hypermyelinated retinal nerve fibers
0007922
Hypoplasia of the corpus callosum
Underdevelopment of part of brain called corpus callosum
0002079
Lower limb spasticity
0002061
Mitral valve prolapse
0001634
Parietal cortical atrophy
0012104
Progressive cerebellar ataxia
0002073
Sensorimotor neuropathy
Nerve damage causing decreased feeling and movement
0007141
Unsteady gait
Unsteady walk
0002317
Urinary incontinence
Loss of bladder control
0000020
5%-29% of people have these symptoms
Abnormal foot morphology
Abnormal feet structure
Abnormality of the feet
Abnormality of the foot
Foot deformities
Foot deformity

[ more ]

0001760
Absent Achilles reflex
Absent ankle reflexes
0003438
Behavioral abnormality
Behavioral changes
Behavioral disorders
Behavioral disturbances
Behavioral problems
Behavioral/psychiatric abnormalities
Behavioural/Psychiatric abnormality
Psychiatric disorders
Psychiatric disturbances

[ more ]

0000708
Distal amyotrophy
Distal muscle wasting
0003693
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

0002015
Foot dorsiflexor weakness
Foot drop
0009027
Gait ataxia
Inability to coordinate movements when walking
0002066
Impaired tactile sensation
Impaired touch sensation
0010830
Impaired vibratory sensation
Decreased vibration sense
Decreased vibratory sense
Diminished vibratory sense
Impaired vibratory sense

[ more ]

0002495
Intention tremor
0002080
1%-4% of people have these symptoms
Ataxia
0001251
Cerebellar vermis atrophy
0006855
Decreased motor nerve conduction velocity
0003431
Hyperactive patellar reflex
Overactive knee reflex
0007083
Impotence
Difficulty getting a full erection
Difficulty getting an erection

[ more ]

0000802
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Peroneal muscle atrophy
0009049
Pes cavus
High-arched foot
0001761
Scoliosis
0002650
Spastic gait
Spastic walk
0002064
Urinary urgency
Overactive bladder
0000012
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
0000007
Decreased number of large peripheral myelinated nerve fibers
0003387
Decreased sensory nerve conduction velocity
0003448
Distal muscle weakness
Weakness of outermost muscles
0002460
Distal sensory impairment
Decreased sensation in extremities
0002936
Falls
0002527
Hammertoe
Hammer toe
Hammertoes

[ more ]

0001765
Hyperreflexia
Increased reflexes
0001347
Impaired smooth pursuit
0007772
Impaired vibration sensation in the lower limbs
Decreased lower limb vibratory sense
Decreased vibratory sense in lower limbs
Decreased vibratory sense in the lower extremities
Decreased vibratory sense in the lower limbs
Diminished vibratory sensation in the legs

[ more ]

0002166
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

0003593
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation

[ more ]

0001249
Loss of Purkinje cells in the cerebellar vermis
0007001
Onion bulb formation
0003383
Progressive gait ataxia
0007240
Progressive truncal ataxia
0007221
Scanning speech
Explosive speech
0002168
Spastic ataxia
0002497
Swan neck-like deformities of the fingers
0006150
Upper motor neuron dysfunction
0002493

Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Spastic ataxia Charlevoix-Saguenay type. Click on the link to view a sample search on this topic.