Muscular dystrophy

Key points about muscular dystrophy

  • Muscular dystrophy (MD) is the name of a group of inherited conditions causing muscle weakness that gets worse over time
  • It's caused by mutations (changes) in genes you inherit from your parents. Depending on the exact type of faulty gene and faulty protein, different types of muscle weakness result. 
  • These types of MD vary in terms of when symptoms are most likely to emerge, which muscles they affect, how severe the symptoms are and whether they affect your life expectancy.
  • There's no cure for MD, but there is treatment and support to help you manage your condition.
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In most cases, MD runs in families. That means it occurs because you have inherited a faulty gene from one or both of your parents. Occasionally, a spontaneous gene mutation can occur in someone with no family history of MD.

The mutations (changes) are in the genes responsible for healthy muscle structure and function. They lead to the cells that should maintain your muscles no longer being able to do so. The cells affected determine which type of MD you develop.

Location of muscle weakness associated with the different types of dystrophy

Image credit: Mantas1234512345 via Wikimedia Commons


There are several recognised types of muscular dystrophy (MD). These are described below.

Duchenne muscular dystrophy (DMD)

DMD is the most common of the muscular dystrophies. It affects about 1 out of every 3,600 baby boys born. DMD is characterised by progressive difficulty in walking and performing everyday activities. The symptoms usually appear before the age of 6 and may appear as early as infancy. Typically, the first noticeable symptom is a delay of motor milestones, including sitting and standing independently. Find out more about DMD(external link).

Becker muscular dystrophy (BMD)

BMD is considered to be a milder form of DMD, as both are caused by mutations in the same gene and have similar symptoms. BMD has a later onset and slower progression. BMD occurs in about 1 in 30,000 live male births. Find out more about BMD(external link).

Manifesting carriers

A manifesting carrier is a female who displays symptoms of a condition that usually only affects males, such as BMD and DMD. Although it is a commonly held belief that carriers merely pass on the disease and are unaffected, female carriers can have similar muscular weakness as affected males. This condition can occur with no known family history of BMD or DMD, so all females who are suspected of having any form of muscular dystrophy should be tested to determine if they could be a manifesting carrier because of the genetic implications. Find out more about manifesting carriers(external link).

Congenital muscular dystrophy (CMD)

CMD causes muscle weakness within the first six months of life. It is rare, affecting about 1 in 50,000 babies and both males and females are equally likely to have this condition. Find out more about CMD(external link).

Emery-Dreifuss muscular dystrophy (EDMD)

EDMD mainly affects muscles used for movement (skeletal muscles) and heart (cardiac) muscle. It affects males and females with first symptoms usually occurring between the ages of 17 and 40. Early symptoms include joint deformities called contractures, which restrict the movement of certain joints, especially elbows, ankles and neck. Find out more about EDMD(external link).

Facioscapulohumeral dystrophy (FSH)

FSH is the third most common muscular dystrophy. It affects about 1 in 20,000 people of Caucasian origin. In FSH the muscles typically affected are those of the face, shoulder blades and upper arms. Find out more about FSH(external link).

Limb girdle muscular dystrophy (LGMD)

LGMD affects the voluntary muscles of the hip and shoulder areas, called the limb girdles. These muscles weaken and waste away (atrophy) and may involve other muscles over time. The onset of LGMD can occur in childhood or symptoms may not be apparent until adolescence or adulthood. Males and females are equally affected. Find out more about LGMD(external link).

Myotonic dystrophy (DM)

Because the Latin name is Dystrophia Myotonica, this condition is known as DM. It is a multi-systemic disorder, which means that the effects are not limited to the voluntary muscle system, but can also affect tissues and organs throughout the body. DM affects both males and females and the age of onset can be from birth to old age. It is a rare condition with three different types, of which 2 affect about 1 in 8,000 people and the third only 1 person in 100,000. Find out more about DM(external link).

Oculopharyngeal muscular dystrophy (OPMD)

OPMD is an inherited condition that appears in early middle age. Progressive drooping of eyelids and weakness of muscles around the eyes is the first symptom, followed by difficulty swallowing food. Find out more about OPMD.(external link)

The main symptom of MD is muscle weakness. Different types of MD affect different muscle groups in your body. The muscle weakness may be mild, moderate or severe. The different types of MD vary as to how quickly or slowly the weakness progresses.

Symptoms can start anywhere between birth and middle age, depending on the type of MD. In young babies, the muscle weakness may be noticed as floppiness. In older babies and young children, the weakness may show up as a delay in learning to hold up their head, sit up, crawl or walk.

Other symptoms include:

  • muscle wasting – your muscles become thin
  • muscle hypertrophy – bulkier than normal muscles, even though they work less well
  • aches or pains in your muscles
  • contractures – tight joints, due to tightness of your muscles or reduced movement of your joints
  • in some cases, symptoms of heart disease without much muscle weakness.

MD is diagnosed based on the specific presentation of muscle weakness, with the pattern determining the type of MD. Diagnosis can now generally be confirmed by gene tests. Other people in the family can also be tested to see if they have a muscular dystrophy gene.

As there is currently no cure for MD, treatment is aimed at helping you to manage the condition. As different types of MD can cause different issues, the treatment you receive will be tailored to your needs.

Treatments can include physiotherapy to help you maintain muscle function. Starting exercises early on can help keep your muscles flexible and strong. You may need braces, which can help keep your muscles and tendons stretched and flexible, slowing the progression of contractures. Braces can also aid movement by providing support for weakened muscles. Depending on the extent of your mobility, you may be advised to use different mobility aids such as canes, walkers and wheelchairs.

To help you maintain your independence, occupational therapy is important to learn new ways of doing things, make adjustments to your immediate living area and provide you with appropriate equipment to assist you.

With time, your respiratory muscles also weaken putting you at risk of chest infections, sleep apnoea and respiratory failure. To prevent infections, it's important to be vaccinated for pneumonia and to keep up to date with influenza shots. For sleep apnoea, to help you breathe, you may need a device to improve oxygen delivery to your lungs.

Some types of MD may mean that you are at increased risk of heart problems, because of the weakening of your heart muscles. It's important that your heart function is assessed regularly once MD has been diagnosed. For Duchenne and Becker MD, an electrocardiogram (ECG) examination of your heart rhythm will be carried out at regular intervals, and you may also have an echocardiogram from time to time. If any damage to your heart is detected, you may be referred to a cardiologist (heart specialist) for further tests and possibly more frequent monitoring.

In some types of MD, such as Oculopharyngeal muscular dystrophy, that affect the throat and eye muscles, you may experience swallowing difficulties and droopy eyelids. There are various treatments that can help with these problems. 

Life expectancy varies depending on the type of MD. However, due to advances in treatment and care, people with MD now live longer. With the most common type of MD, Duchenne muscular dystrophy, survival into the early 30s is becoming more common, and there are cases of men living into their 40s and 50s.

Get support for yourself and your family through counseling, joining Muscular Dystrophy New Zealand, talking to friends and family about your experience.

Exercise as much as you are able to. The health benefits can impact on maintaining your mobility, managing your pain levels and helping with your general standard of living.

Get the recommended vaccinations for people with neuromuscular diseases, such as the annual flu and pneumococcal vaccines.

The Muscular Dystrophy Association NZ(external link) offers educational, emotional, financial, personal and workplace assistance. MDA has a support network of more than 600 members throughout New Zealand who want to be in touch with others living with neuromuscular conditions. There are regional branches and you can phone the national office on 0800 800 337.

Duchenne muscular dystrophy(external link) Patient Info Professional, UK, 2016
Beckers muscular dystrophy(external link) Patient Info Professional, UK, 2016
Facioscapulohumeral muscular dystrophy(external link) Patient Info Professional, UK, 2016
Limb girdle muscular dystrophy(external link) Patient Info Professional, UK, 2016
Neuromuscular conditions(external link) Goodfellow eLearning, 2019

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