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Spinocerebellar ataxia type 1
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Spinocerebellar ataxia type 1

Spinocerebellar ataxia type 1 (SCA1) is a progressive neurological disorder characterized by problems with coordination and balance, speech and swallowing difficulties, and other movement impairments, typically appearing in early adulthood.

Overview

Spinocerebellar ataxia type 1 (SCA1) is a condition characterized by progressive problems with movement. People with this condition initially experience problems with coordination and balance (ataxia). Other signs and symptoms of SCA1 include speech and swallowing difficulties, muscle stiffness (spasticity), and weakness in the muscles that control eye movement (ophthalmoplegia). Eye muscle weakness leads to rapid, involuntary eye movements (nystagmus). Individuals with SCA1 may have difficulty processing, learning, and remembering information (cognitive impairment).

Over time, individuals with SCA1 may develop numbness, tingling, or pain in the arms and legs (sensory neuropathy); uncontrolled muscle tensing (dystonia); muscle wasting (atrophy); and muscle twitches (fasciculations). Rarely, rigidity, tremors, and involuntary jerking movements (chorea) have been reported in people who have been affected for many years.

Signs and symptoms of the disorder typically begin in early adulthood but can appear anytime from childhood to late adulthood. People with SCA1 typically survive 10 to 20 years after symptoms first appear.

Frequency

SCA1 affects 1 to 2 per 100,000 people worldwide.

Causes

Mutations in the ATXN1 gene cause SCA1. The ATXN1 gene provides instructions for making a protein called ataxin-1. This protein is found throughout the body, but its function is unknown. Within cells, ataxin-1 is located in the nucleus. Researchers believe that ataxin-1 may be involved in regulating various aspects of producing proteins, including the first stage of protein production (transcription) and processing RNA, a chemical cousin of DNA.

The ATX

Frequently Asked Questions

Early planning involves regular assessments of balance and gait, use of assistive devices (e.g., canes, walkers), and home modifications (grab bars, ramps). Physical therapy can strengthen core muscles and improve fall prevention. Engaging in adaptive sports or low‑impact activities (like swimming) can preserve fitness. Additionally, advance care planning, including discussions about future care needs and legal documents, helps ensure that the patient’s preferences are respected as the disease progresses.===
Early signs often include subtle gait instability, a tendency to sway or stumble, and mild difficulty with fine motor tasks such as buttoning a shirt or writing. Some patients notice a slight slowness in initiating movements or a mild tremor in the hands. These symptoms usually appear in the late teens to early twenties.
Speech‑language therapy focuses on improving articulation and voice quality, while swallowing therapy (logopedics) can teach safe swallowing techniques and dietary modifications. In more advanced stages, a speech‑language pathologist may recommend adaptive communication devices or a feeding tube if aspiration risk is high. Medications such as anticholinergics can reduce drooling, and speech‑enhancing drugs may be trialed under specialist guidance.
Diagnosis starts with a detailed neurological exam and family history. A definitive diagnosis requires genetic testing for the CAG repeat expansion in the ATXN1 gene, typically performed via a blood sample. Some centers also use MRI to look for characteristic cerebellar atrophy, but genetic testing is the gold standard.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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