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Spinocerebellar ataxia type 36
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Spinocerebellar ataxia type 36

Spinocerebellar ataxia type 36 (SCA36) is a progressive neurological condition characterized by movement coordination issues, muscle atrophy, and speech difficulties, typically appearing in mid-adulthood.

Overview

SCA36 is a condition that causes progressive problems with movement. Symptoms usually begin in a person's forties or fifties. While the condition is progressive, affected individuals typically maintain a normal lifespan and remain mobile for 15 to 20 years following diagnosis.

Symptoms

  • Movement and coordination: Initial symptoms include ataxia (problems with balance and coordination), exaggerated reflexes (hyperreflexia), and speech difficulties (dysarthria).
  • Muscle atrophy: Fasciculations (twitches) and wasting of the tongue muscles, which can cause difficulty swallowing. Over time, muscle atrophy also occurs in the legs, forearms, and hands.
  • Eye and ear issues: Potential involuntary eye movements (nystagmus), rapid eye movements (saccades), trouble moving eyes side-to-side (oculomotor apraxia), droopy eyelids (ptosis), and sensorineural hearing loss.
  • Brain changes: Imaging often shows atrophy of the cerebellum (the area coordinating movement). In older individuals, frontal lobe atrophy may lead to a loss of executive function, such as planning and problem-solving.

Causes

SCA36 is caused by mutations in the NOP56 gene. The mutation involves a massive expansion of a hexanucleotide repeat (GGCCTG) in the gene's intron 1. While healthy individuals have 3 to 14 repeats, those with SCA36 have at least 650 repeats.

This expansion disrupts the structure of NOP56 mRNA, forming clumps called RNA foci within the nuclei of neurons. These foci trap other essential proteins. Additionally, the expansion may reduce the activity of a nearby gene, MIR1292, leading to an increase in glutamate receptors. This overexcites neurons, disrupting communication and contributing to cell death, particularly in the cerebellum.

Inheritance

SCA36 is inherited in an autosomal dominant pattern, meaning one copy of the altered gene is sufficient to cause the disorder. In many cases, the number of DNA repeats increases when passed from parent to child, a phenomenon known as anticipation, which can lead to an earlier onset of symptoms in subsequent generations.

Frequently Asked Questions

Diagnosis combines neuroimaging and molecular testing. An MRI often shows cerebellar atrophy, sometimes with frontal‑lobe thinning in later stages. Definitive confirmation requires a repeat‑primed PCR or Southern blot that detects the expanded GGCCTG hexanucleotide repeat in intron 1 of NOP56.
The first clues are usually subtle balance problems, frequent stumbling, or a feeling of “clumsiness” that appears in the 40‑50 year age range, often accompanied by mild speech slurring (dysarthria) or unexplained muscle twitches (fasciculations). If these symptoms run in a family with known cerebellar disease, a neurologist will typically recommend genetic testing for the NOP56 repeat expansion.
There is no disease‑modifying drug yet, but multidisciplinary care can preserve function: physical therapy focuses on gait stability and balance; speech‑language therapy helps maintain intelligible speech and swallowing safety; occupational therapy addresses hand dexterity; and medications such as baclofen or gabapentin may reduce painful muscle cramps or spasticity. Regular audiology follow‑up is advised because sensorineural hearing loss can be part of the phenotype.
SCA36 follows an autosomal‑dominant pattern. Each child of an affected parent has a 50 % chance of inheriting the expanded repeat. Testing of at‑risk adult relatives can be done with a blood DNA test, and pre‑symptomatic counseling is recommended because the disease typically manifests in mid‑adulthood, allowing families to plan surveillance and lifestyle adjustments.
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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