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Neuromuscular diseases

Spinocerebellar ataxia type 3 (Machado-Joseph disease)

An inherited disease of the nervous system. Balance and coordination of movement gradually worsen. Symptoms usually begin in adulthood.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

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This page is translated from the Turkish original.

This disease is followed through the “Neuromuscular diseases” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

A piece of DNA in the ATXN3 gene is repeated many more times than normal. As a result, a protein called ataxin-3 is made faulty and forms clumps in the cells. Nerve cells in the cerebellum, brainstem and spinal cord are lost over time. Movement, speech and swallowing are affected.

Which symptoms can occur?

Symptoms usually begin in middle age, but they can also appear in childhood.

  • Balance and walking problems, called ataxia
  • Difficulty speaking and swallowing
  • Muscle stiffness, involuntary muscle contractions and tremor
  • Double vision and problems with eye movements
  • Sleep problems such as restless legs and acting out dreams
  • Numbness, cramps and muscle twitching in the hands and feet
  • Difficulty with memory and planning (in some people)

How is it diagnosed?

The doctor does a neurological examination and asks about the family history. A brain MRI can show shrinking of the cerebellum. The diagnosis is confirmed with a genetic test that looks at the ATXN3 gene.

Treatment and care

There is not yet an approved treatment specific to the disease; research is ongoing. Care is teamwork and is planned according to the symptoms. Physiotherapy and occupational therapy support balance and movement. A walker and grab bars can reduce falls. Speech and swallowing therapy and nutritional support are provided. Treatment aimed at specific symptoms can be given for muscle stiffness, sleep and mood problems. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The disease is passed on through dominant inheritance. For each child of an affected parent, the chance is 1 in 2. As the gene passes from one generation to the next, the number of repeats can increase. Symptoms may then begin earlier and progress faster. Adults without symptoms can choose to have a predictive genetic test. This decision is made together with genetic counselling.

Source: MedlinePlus Genetics: Spinocerebellar ataxia type 3 · NORD: Machado-Joseph Disease · Orphanet: Spinocerebellar ataxia type 3 (ORPHA:98757)

Key facts

How common is it?
Prevalence: 1-9 per 100 000 (Worldwide)
How is it inherited?
Autosomal dominant
When does it usually start?
Adulthood, Childhood

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

We could not find a patient association specific to this disease.

For all rare diseases: Nadir Hastalıklar Federasyonu

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about SCA3

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 5 active interventional studies for this disease. 1 is recruiting now; none has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Neuromuscular diseases: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:98757

No separate ICD-11 code; WHO classifies this disease under: 8A03.16

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.