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Machado-Joseph disease, or spinocerebellar ataxia type 3, is an inherited brain disorder that affects muscle control, which results in a lack of balance and coordination. The condition leads to a progressive lack of coordination in your arms and legs. There’s no cure for Machado-Joseph disease, but medication can help relieve symptoms.
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Machado-Joseph disease (MJD) is an inherited (passed down) ataxia disorder. Ataxia is a degenerative (slowly progressive) condition that affects your nervous system. It can affect your ability to control your muscles, which results in a lack of balance and coordination. Specifically, the condition leads to a progressive lack of coordination in your limbs (arms and legs).
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People with Machado-Joseph disease have a particular, staggering walk and you may also have difficulty swallowing and speaking.
Another name for MJD is spinocerebellar ataxia type 3. It’s the most common type of spinocerebellar ataxia.
Machado-Joseph disease can be broken into three different types. The type depends on when the symptoms started (age of onset) and the severity of symptoms. These types are:
Which Machado-Joseph disease symptoms you experience depends on the type you have.
Type I symptoms are severe and progress rapidly. They may include:
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Type II symptoms gradually get worse over time and may include:
Type III symptoms slowly worsen over time and may include:
Other Machado-Joseph disease symptoms may include:
Several symptoms — and their appearance together — may look like the symptoms of other neurologic disorders, like multiple sclerosis or Parkinson’s disease. Visit a healthcare provider if you notice any new or worsening symptoms, especially if they affect your ability to move and use your body.
A genetic mutation causes Machado-Joseph disease. Specifically, a mutation in the ATXN3 gene on chromosome 14. This segment of DNA abnormally repeats several times. Geneticists call this “CAG” trinucleotide repeats (or triplets). CAG stands for Cytosine-Adenine-Guanine.
In a person without MJD, DNA has between 12 and 43 copies of the CAG trinucleotide. In people with Machado-Joseph disease, DNA contains between 56 and 86 copies of this abnormality. The age at which you start developing symptoms and the severity of your condition are directly related to the number of CAG repeats you have.
The condition is inherited in an autosomal dominant manner. This means only one biological parent has to have the gene for their child to be affected by the condition. You only need to have one copy of the gene to have MJD. If you have Machado-Joseph disease, your biological child has a 50% chance of inheriting it.
MJD is most commonly seen in people of Azorean or Portuguese descent. On an island called Flores in the Azores, 1 in every 140 people has the condition. But the condition can affect any ethnic group.
A healthcare provider will ask about your symptoms and perform a physical examination. Because the condition is inherited, it’s important to discuss your biological family history. If others in your family have symptoms of the disease, ask when their symptoms started and how rapidly they developed.
To confirm a diagnosis, your provider will suggest Machado-Joseph disease genetic testing. Through a genetic test, your provider can look for the number of suspect CAG triplets on your 14th chromosome.
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Unfortunately, there’s no cure for Machado-Joseph disease. MJD treatment consists of medications to manage the symptoms you’re experiencing. These medications may include:
In addition, physical therapy and assistive equipment can help people with their daily activities and movement. For visual symptoms, prism glasses may help reduce double or blurred vision.
Ask your healthcare provider about the possibility of a clinical trial for the condition.
MJD is a genetic condition and it’s not preventable. If you’re concerned about passing on the condition to your biological children, talk to a genetic counselor before planning for pregnancy. It may be possible to do a procedure called in vitro fertilization (IVF) with genetic testing to prevent passing on MJD to your children.
MJD life expectancy varies based on the type you have. For people with type I, life expectancy may be as short as the mid-30s. But people with type II or type III usually have a typical life expectancy.
See your healthcare provider if you notice any Machado-Joseph disease symptoms. If the condition runs in your family, talk to your provider sooner about your risk of developing it.
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If you’ve been diagnosed with MJD, you may wish to ask your healthcare provider the following questions:
A diagnosis of Machado-Joseph disease (MJD) can raise many questions and emotions. Make sure to ask for support from those close to you. And be an active participant in your care — attend all of your healthcare appointments, follow your provider’s instructions and ask questions. You may also consider talking to a mental health counselor who can teach you coping skills. Don’t try to ignore or suppress your feelings. Talk to friends, a counselor or a support group. Remember you’re not alone.
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Last reviewed on 07/26/2024.
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