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Definition

What is myotonic dystrophy?

Myotonic dystrophy is characterized by progressive muscle wasting and weakness. People with this disorder often have prolonged muscle contractions (myotonia) and are not able to relax certain muscles after use. For example, a person may have difficulty releasing their grip on a doorknob or handle. Also, affected people may have slurred speech or temporary locking of their jaw.

How common is myotonic dystrophy?

Myotonic dystrophy is the most common form of muscular dystrophy that begins in adulthood. Please discuss with your doctor for further information.

Symptoms

What are the symptoms of myotonic dystrophy?

People who have myotonic dystrophy have progressive muscle wasting and weakness beginning in their 20’s or 30’s. The muscle wasting and weakness develop in their lower legs, hands, neck and face. They also have stiffness and tightness of their muscles (called myotonia), so they are slow to relax certain muscles after using them. Not being able to release their grip on in a handshake or a doorknob is one example of this problem.

In addition to muscle weakness and wasting, people who have myotonic dystrophy have clouding of the lens in their eyes (cataracts), and irregularities in the electrical control of their heartbeat (cardiac conduction defects).

Men who have myotonic dystrophy have changes in their hormones that can cause balding and sometimes the inability to father a child (infertility).

Babies who are born with signs and symptoms of myotonic dystrophy have congenital myotonic dystrophy. They have weakness of all their muscles, breathing problems, and developmental delays including mental retardation. Sometimes these medical conditions are so severe they may cause death.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.

Causes

What causes myotonic dystrophy?

Myotonic dystrophy is an inherited disease where a change, called a mutation, has occurred in a gene required for normal muscle function. The mutation prevents the gene from carrying out its function properly. The change is an autosomal dominant mutation, which means one copy of the altered gene is sufficient to cause the disorder. As a result, affected individuals have a 50% chance of passing on the mutated gene to their children. A child is equally likely to have inherited the mutated gene from either parent. If both parents do not have the disease, their children cannot inherit it.

Risk factors

What increases my risk for myotonic dystrophy?

Please discuss with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is myotonic dystrophy diagnosed?

Myotonic dystrophy is diagnosed by doing a physical exam. A physical exam can identify the typical pattern of muscle wasting and weakness and the presence of myotonia. A person with myotonic dystrophy may have a characteristic facial appearance of wasting and weakness of the jaw and neck muscles. Men may have frontal balding.

There are several laboratory tests that can be used to clarify the clinical diagnosis of myotonic dystrophy. One test, called electromyography (EMG), involves inserting a small needle into the muscle. The electrical activity of the muscle is studied and usually shows characteristic patterns of muscle electrical discharge.

The definitive test for myotonic dystrophy is a genetic test. For this test, a blood sample is taken to identify the altered gene (mutation) within the chromosomes which are contained within the white blood cells. Gene alterations in two genes – CNBP and DMPK – cause myotonic dystrophy. Myotonic dystrophy Type 1 is caused by a mutation in the DMPK gene. Type 2 myotonic dystrophy is caused by a mutation in the CNBP gene. Mutations in each of these genes involve a short segment of DNA that is abnormally repeated many times. This abnormal repetition forms an unstable region of the gene. These changes keep cells in the muscles and other body tissues from functioning normally, leading to signs and symptoms of myotonic dystrophy.

How is myotonic dystrophy treated?

There is currently no cure or specific treatment for myotonic dystrophy. Ankle supports and leg braces can help when muscle weakness gets worse. There are also medications that can lessen the myotonia. Other symptoms of myotonic dystrophy such as the heart problems, and eye problems (cataracts) can also be treated.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage myotonic dystrophy?

Please discuss with your doctor for further information.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: November 7, 2017 | Last Modified: November 7, 2017

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