Emery-Dreifuss Muscular Dystrophy
Fact Sheet # 06
Is Emery-Dreifuss Muscular Dystrophy also known by other names?
No, it is only known as Emery-Dreifuss muscular dystrophy.
What is Emery-Dreifuss Muscular Dystrophy?
Like other muscular dystrophies it is a wasting disorder of muscle. It usually begins in childhood or adolescence. The features that make it unique and different from other muscular dystrophies are the early development of muscle contractures, the distribution of muscle weakness, and the fact that the heart may be affected in a particular way. It was named after Drs Emery and Dreifuss, who first described it.
What causes Emery-Dreifuss Muscular Dystrophy?
The gene that is responsible for the X-linked form of Emery-Dreifuss has been identified. This gene is located on the X chromosome and codes for a protein called emerin. Mutations within the emerin gene have been associated with ED muscular dystrophy.
What are the symptoms?
This is a tightening and shortening of certain muscle groups so that the joints that are involved become increasingly difficult to move. Such contractures are common at a late stage in most muscle wasting disorders and result from inactivity. In this disorder muscle contractures develop very early or before there is any marked muscle weakness. Contractures limit the elbow straightening so that the arms are often held in a semi-flexed way, they result in a tendency to walk on the toes, and they limit forward bending of the neck. The heart is affected in a distinctive way, referred to as “heart block” (see 5).
Which muscles are affected?
In the upper limbs weakness affects mainly the shoulders and upper arms. In the lower limbs, unlike most other dystrophies, weakness affects the lower legs first. This distribution of muscle weakness is sometimes referred to as “scapuloperoneal”. At first there is difficulty in raising the arms above the head and lifting heavy objects, and a tendency to trip over carpets. Later on the hip and thigh muscles also become affected so that climbing stairs becomes increasingly difficult, as does rising from a chair without assistance. Often the heart is affected and this is referred to as “heart block”. The heart rate is often abnormally slow, palpitations may occur (which feel like “fluttering” in the chest – this is not uncommon in normal individuals and alone would not be a cause for concern), as well as attacks of giddiness and fainting spells. Increasing tiredness and breathlessness may occur.
How is Emery-Dreifuss Muscular Dystrophy inherited?
The condition is inherited and can therefore affect other members of the family. In most families it is inherited as a sex-linked (X-linked) trait and therefore only affects males and is carried by unaffected females. All the sons of an affected male will be unaffected but all his daughters will be carriers. With regard to the offspring of a woman who is a carrier, on average each of her daughters has a 50% chance of also being a carrier, and on average each of her sons has a 50% chance of being affected. Although the disorder is inherited in most families as an X-linked trait, in a few rare families a similar disorder may be inherited as an autosomal dominant trait. Here, both males and females can be affected, and on average each son or daughter of an affected parent has a 50% chance of also becoming affected. In some cases no family history exists for the disorder, and only one individual in the family may be affected. In these cases the disorder has arisen as a result of a new mutation in the affected individual. He may then later transmit the mutation to his children. For the above reasons it is very important to seek professional advice if you are at all concerned about the risks to your children and other relatives. As this is a genetic condition, genetic counselling is strongly recommended. Genetic counselling provides information on the inheritance pattern, risks to other family members, prognosis, psycho-social support, as well as information about diagnostic testing, carrier testing, preclinical and prenatal testing (where available).
How is Emery-Dreifuss Muscular Dystrophy diagnosed?
The diagnosis is mainly made on the clinical features of the disorder. A specialist will be able to detect whether the heart muscles are affected. A blood test can also be used for diagnosis of the X-linked form, since the emerin gene has been identified to carry multiple mutations that cause ED muscular dystrophy.
Is there a cure?
The condition is less severe than many other forms of muscular dystrophy and though life expectancy may be shortened, many affected individuals can expect to reach middle age or later. However, having an adequate diet and maintaining good general health are very important as in all muscular dystrophies.
Is there any treatment?
The condition is less severe than many other forms of muscular dystrophy and though life expectancy may be shortened, many affected individuals can expect to reach middle age or later. Regular gentle exercise, which is tolerated without causing stress, is beneficial. Hard physical exercise (weight training for example) should be avoided. It is essential to eat a well balanced diet, to include plenty of roughage and to avoid becoming overweight since this will only overburden the already weakened muscles. Division of the heel cords can be helpful for walking. Other operations can be indicated in individual cases where expert advice from a neurologist and orthopaedic surgeon should be sought. Because the heart may be affected and could complicate an operation, the anaesthetist must be told of the diagnosis before any operation is undertaken. If the heart becomes affected, and not every person is affected in this way, then there is the danger of heart failure. If, however, the doctor finds that the heart block is developing, then he/she may recommend the insertion of a pacemaker. This small gadget is inserted just below the skin of the chest and prevents further problems arising by ensuring that the heart thereafter beats normally. The future is more hopeful than in the past. Not only through the use of pacemakers in cases with heart disorder, but the gene responsible for Emery-Dreifuss MD has been identified. This opens the way for DNA diagnoses, and eventually an effective treatment.
Is there a risk during anaesthesia?
Yes, due to the fact that the heart muscles may be affected it is very important that the anaesthesiologist is informed prior to the operation. It is always recommended that the presence of a muscular disorder be mentioned to your doctor.
Has research been conducted on in South Africa?
No, to date no research has been conducted in South Africa. However, there are several international research programmes underway to find the cause of this type of muscular dystrophy.
Please contact the MDF for further information.
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