National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Spinocerebellar ataxia 18



Other Names:
SCA18; Spinocerebellar ataxia type 18; Sensorimotor neuropathy with ataxia autosomal dominant; SCA18; Spinocerebellar ataxia type 18; Sensorimotor neuropathy with ataxia autosomal dominant; SMNA See More
Categories:
This disease is grouped under:

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

Orpha Number: 98771

Definition
Spinocerebellar ataxia type 18 (SCA18) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I; see this term). It is characterized by sensory neuropathy and cerebellar ataxia.

Epidemiology
Prevalence is unknown. Only 26 cases in a 5-generation American family of Irish ancestry have been reported to date.

Clinical description
Onset is in the 2nd and 3rd decades of life with symptomatic onset ranging from 13 to 27 years. Patients initially present with axonal sensory neuropathy, while cerebellar ataxia and motor neuron dysfunction develop later.

Etiology
SCA18 has been linked to chromosome 7q22-q23 but the responsible gene mutation has not yet been identified. Both SCA3 and SCA4 are also associated with a peripheral neuropathy and should be taken into account in the differential diagnosis.

Prognosis
Prognosis is unclear. However, mean disease duration from age at onset of illness to age at last examination is about 24 years in the reported cases.

Visit the Orphanet disease page for more resources.
Last updated: 5/1/2011

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.

Showing of 27 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Areflexia
Absent tendon reflexes
0001284
Gait ataxia
Inability to coordinate movements when walking
0002066
Muscle weakness
Muscular weakness
0001324
Sensory impairment 0003474
30%-79% of people have these symptoms
Dysarthria
Difficulty articulating speech
0001260
Dysmetria
Lack of coordination of movement
0001310
Hearing impairment
Deafness
Hearing defect
[ more ]
0000365
Hyporeflexia of lower limbs 0002600
Lower limb hyperreflexia
Overactive lower leg reflex
0002395
Muscle fibrillation 0010546
Pes cavus
High-arched foot
0001761
Sensorimotor neuropathy
Nerve damage causing decreased feeling and movement
0007141
5%-29% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
0001272
Head tremor 0002346
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Peripheral axonal neuropathy 0003477
Skeletal muscle atrophy
Muscle degeneration
Muscle wasting
[ more ]
0003202
Titubation 0030187
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Babinski sign 0003487
Dysdiadochokinesis
Difficulty performing quick and alternating movements
0002075
Hyporeflexia
Decreased reflex response
Decreased reflexes
[ more ]
0001265
Limb muscle weakness
Limb weakness
0003690
Onset
Age symptoms begin
0003674
Progressive gait ataxia 0007240
Sensory axonal neuropathy 0003390
Tremor 0001337
Showing of 27 |
Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources


If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources


Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.

Patient Registry

  • Coordination of Rare Diseases at Sanford (CoRDS) hosts a specific registry for patients with ataxia in partnership with the National Ataxia Foundation. The goal of the CoRDS registry is to connect as many patients and researchers as possible to help advance treatments and cures for rare diseases. The CoRDS registry is free for patients to enroll and for researchers to access.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease


Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources


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.

Where to Start

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 Spinocerebellar ataxia 18. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.