An inherited brain disease that negatively affects the ability to control muscles is called Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3. Usually, it causes a progressive lack of coordination in the arms and legs. Unfortunately, it is not possible to cure this condition, but with early diagnosis and treatment, you can relieve the symptoms and slow down the progression.
In other words, MJD is an inherited ataxia disorder, which is a degenerative condition that impacts the nervous system. In most cases, people with this inherited brain disease have a specific staggering walk and problems with speaking and swallowing. Furthermore, MJD is the most common form of spinocerebellar ataxia.
Types of Machado-Joseph Disease
Experts have divided this condition into 3 types depending on when the symptoms start and their severity. For example:
- Type I (MJD-I) – The first type of MJD often causes severe symptoms that progress quickly. In most cases, it affects people between the ages of 10 and 30.
- Type II (MJD-II) – This form of MJD often starts between the ages of 20 and 50, and the symptoms tend to progress gradually.
- Type III (MJD-III) – This is the last form of MJD, and the symptoms it causes progress slowly over the years. Mostly, it occurs in people between the ages of 40 and 70.
Symptoms
Usually, people with MJD experience different symptoms because they depend on the following factors. For example, the severity and type of the condition, existing health problems, age, and others. Check some examples below:
Type I Symptoms
- Speaking and swallowing problems (dysphagia)
- Hypertonia (increased muscle tone)
- Ataxia (unusual body movements)
- Proptosis (also known as bulging eyes)
- Staggering gait
- Muscle stiffness
- Severe muscle spasms in the arms and legs
Type II Symptoms
- Uncontrollable and prolonged muscle spasms (also known as spasticity)
- Difficulty coordinating movements of the arms and legs
- Poor reflexes
Type III Symptoms
- Tingling, numbness, cramps, and pain in the arms, hands, legs, and feet (also known as neuropathy)
- Unsteady gait
- Atrophy (loss of muscle tissue)
- Muscle twitching
- Diplopia (double vision)
- Nystagmus (uncontrolled eye movements)
- Hand trembling
- Problems with balance and coordination
- Facial or tongue twitching
- Sleep disorders
- Chronic low back pain
Some of the previous symptoms are very similar to those caused by multiple sclerosis (MS) or Parkinson’s disease. That’s why you should see a doctor for a diagnosis if any of the symptoms listed above occur.
Causes and Risk Factors
MJD is caused by a mutation (change) in the ATXN3 gene on chromosome 14. This part of the DNA abnormally repeats multiple times. Sometimes, geneticists call this gene mutation “CAG” trinucleotide repeats or triplets. The medical term CAG stands for Cytosine-Adenine-Guanine.
While a person without this condition has between 12 and 43 copies of the CAG trinucleotide, those who suffer from MJD have between 56 and 86 copies. In general, the age of onset directly depends on the number of CAG repeats you have.
This brain disorder is inherited in an autosomal dominant pattern. It means that even one abnormal gene is enough to cause the condition. Moreover, if you have the abnormal gene that causes MJD, there is a 50% chance of passing it to your children in the future.
In addition, doctors have identified some factors that may elevate your risk of developing MJD. Commonly, it appears in people of Azorean or Portuguese descent. For instance, 1 in every 140 people on an island called Flores in the Azores develops MJD. However, any ethnic group can develop this disorder.
Complications
Usually, people with MJD experience the following complications. Consult with your doctor about ways to reduce the risk of developing them. Examples include:
- Ataxia
- Spasticity or rigidity
- Weakness
- Severe dysphagia
- Vision changes – For example, double vision, blurred vision, difficulty focusing eyes, uncontrolled eye movements, and others
- Impaired memory
- REM sleep behavior disorder
- Restless legs syndrome
- Urinary problems
- Mental health disorders (such as depression, emotional difficulties, and others)
The previous list does not contain a full list of MJD complications.
How to Prevent Machado-Joseph Disease?
Unfortunately, it is not possible to prevent this disorder. However, if you can perform some genetic tests before pregnancy to check for the abnormal gene that causes MJD. It is very important to understand the risks of having children with MJD. If you have a family history of the disease, you can choose a procedure called in vitro fertilization (IVF). For more details, discuss it with your doctor.
Diagnosis
Usually, the diagnosis of this brain disorder begins with a physical examination and questions about your symptoms and family history. However, to confirm or rule out this disorder, doctors often perform a genetic test. To perform this test, doctors will take a sample of blood to check for CAG triplets on your 14th chromosome.
Treatment
There is no way to cure this condition, and the treatment goal is to relieve the symptoms, prevent serious complications, and improve your quality of life. Check below some symptoms often recommended by doctors for people with MJD:
- Baclofen or Botulinum toxin – These medicines are used to relieve the symptoms of MJD, such as dystonia and muscle spasms.
- Levodopa therapy – This therapy is primarily used to ease slowness and stiffness caused by this disease, but may also address other symptoms.
Sometimes, people with MJD also use physical therapy and assistive equipment to perform their daily activities. You can also ask your doctor about the possibility of a clinical trial.
Frequently Asked Questions
What is the life expectancy of someone with Machado-Joseph disease?
While the second and third types of this brain disorder do not affect life expectancy, the first type (the most severe form of MJD) may negatively affect your life expectancy, and it can be as short as the mid-30s. For more details, discuss it with your physician.
When should I see my healthcare provider?
In general, if you experience any symptoms that resemble Parkinson’s disease, multiple sclerosis, or Machado-Joseph disease, you should visit a doctor immediately. Early diagnosis and proper treatment can help slow down the progression of the disease and prevent life-threatening complications.
How many people have Machado-Joseph disease?
This inherited brain disorder affects about 1 to 5 in every 100,000 people worldwide. Ask your healthcare provider if you have any other questions.
