Where to get help:
* Your Doctor
* Muscular Dystrophy Association Tel. (03) 9320 9555
Things to remember:
* Muscular dystrophies are inherited muscle diseases that lead to progressive weakness and irreversible wasting of muscle tissue.
* There is no cure for any of the 60 neuromuscular disorders.
* The symptoms of different muscular dystrophies may vary.
Myotonic Dystrophy is the most common adult form of muscular dystrophy. Unlike the other muscular dystrophies, the muscle weakness is accompanied by myotonia (delayed relaxation of muscles after contraction) and by a variety of abnormalities in addition to those of muscle. The disorder is also known as Steinert's disease and dystrophia myotonica.
No. Myotonic Dystrophy is a progressive degenerative disorder. There are some therapies that can reduce some of the effects. The O’Sullivan brothers were all diagnosed at a very young age.
The first muscles to be affected by weakness are those of the face, neck, hands, forearms, and feet. Myotonic Dystrophy can affect the tissues and organs of many body systems. Consequently, Myotonic Dystrophy may present itself in what one expert has called a "bewildering variety of ways".
The effects can include cardiac disease, cataracts, testicular atrophy, respiratory impairment and adverse reactions to anaesthesia, difficulty in swallowing (dysphagia) and other gastrointestinal tract involvement, mental disorders (including mental retardation), excessive output of insulin and abnormal carbohydrate metabolism, and excessive sleeping.
There is advanced gene research being carried out in a number of countries with the focus of repairing the faulty genes that cause Myotonic Dystrophy. The most advanced research is for Duchenne’s Muscular Dystrophy.
Myotonic Dystrophy originates due to expansions of the CTG triplet of the DMPK gene in our DNA, which through a well documented process, abduct MBNL proteins and prevent them from carrying out their normal functions within the cell.
Research has discovered molecules that are able to increase the expression of MBNL proteins, which are crucial for the disease, and that way prevent many of the alterations present in the murine and cellular models of the disease.
Fifty percent of those with the disorder show visible signs by about twenty years of age, but a significant number do not develop clear-cut symptoms until after age fifty. However, when Myotonic Dystrophy is suspected (because it is present in other members of the family), careful examination may reveal typical abnormalities before obvious symptoms appear.
Myotonic Dystrophy is transmitted from generation to generation by men or women who themselves have inherited the defective gene and have the disease. Because the defective gene is dominant, only one Myotonic Dystrophy gene derived from either the father or mother, is required to produce the disease in an offspring. There is a 50-50 chance that, if one parent has the disease, such transmission will occur. The technical term for this mode of inheritance is 'autosomal dominant'.
The severity of the condition tends to get worse with successive generations in a family. Geneticists call this phenomenon ‘anticipation’. This can lead to a very severe form of Myotonic Dystrophy with onset in infancy.
The course of Myotonic Dystrophy varies widely, even in the same family. On the one hand, there are people with the disorder whose symptoms are so mild they hardly know anything is wrong. Whatever muscle weakness they experience is something they take for granted and adapt to.
In some cases, the only symptom may be a cataract. Nevertheless, these people do have Myotonic Dystrophy and can transmit a serious case of the disease to their children.
For the most part, weakness and wasting slowly progress to the point of some disability, moving beyond the muscles originally involved to those of the shoulders, hips, and thighs. As a rule, disability rarely becomes severe until fifteen to twenty years after the onset of symptoms. The older a person is when muscle weakness is first noticed, the slower is the progression and the less serious the consequences.
The congenital muscular dystrophies (CMDs) are a very mixed group of conditions with varying degrees of severity and rates of progression. Congenital means 'from birth' and in most cases of congenital muscular dystrophy, the initial symptoms are present at birth or in the first few months.
Babies with congenital muscular dystrophy often have low muscle tone or floppiness and may have reduced movements. Other common signs are contractures (tightness) in the ankles, hips, knees and elbows. Some babies may also have trouble breathing and feeding. Some improvement often occurs in childhood and the disease shows little or no progression.
There are at least five different types of CMD, which are caused by alterations in different genes. Both parents usually carry the altered gene, but are unaffected by the condition. The affected child inherits two copies of the altered gene – one from each parent.
Many people think that muscular dystrophy is exclusively a childhood disorder. However, it can occur at any point in your life.
As well as Myotonic Dystrophy, FSH and Becker MD, three other types that can occur later in life include:
People with Limb-girdle Muscular Dystrophy have generally inherited the altered gene from both parents. This type usually occurs in the first to third decades of life and involves:
This form of muscular dystrophy is fairly rare and affects the extraocular (eye) muscles, leading to drooping eyelids. Eventually, the muscles associated with swallowing may be affected. It usually occurs in adulthood.
This is the rarest of the muscular dystrophies, although it is comparatively more common in Sweden. It affects the small muscles of the extremities (arms and legs).