What are the other Names for this Condition? (Also known as/Synonyms)
- Benign Scapuloperoneal Muscular Dystrophy with Early Contractures
- EDMD (Emery-Dreifuss Muscular Dystrophy)
- Emery-Dreifuss Syndrome
What is Emery-Dreifuss Muscular Dystrophy? (Definition/Background Information)
- Emery-Dreifuss Muscular Dystrophy (EDMD) is a rare, progressive condition which affects the skeletal muscles (voluntary muscles used for movement) and the cardiac (heart) muscles
- The earliest features of the disorder are muscle contractures (permanent shortening of the muscle) and restricted movements of the joints (at the elbows, ankles, and neck)
- In almost all individuals, heart anomalies such as irregular heart rhythms also develop due to abnormalities in the electrical signaling
- The only risk factor for Emery-Dreifuss Muscular Dystrophy is a family history of the disorder. The disorder is caused by mutation in two genes, one being LMNA gene and the other, EMD gene
- The common signs and symptoms associated with Emery-Dreifuss Muscular Dystrophy are contractures in the elbow, spine, and ankle, weakness of the muscles of the arms and lower legs, and heart conduction abnormalities
- The diagnosis of this genetic disorder includes a complete medical history, a thorough physical exam and tests such as electromyography and muscle biopsy
- There is no definitive treatment and prevention of Emery-Dreifuss Muscular Dystrophy. The management is aimed more at treating the symptoms and controlling the complications (if any)
- The prognosis depends on the severity of the muscle contractures and the degree of cardiac involvement
Emery-Dreifuss Muscular Dystrophy is a genetic disorder caused by mutation in certain genes. There are 3 different inherited types of this disorder:
- X-linked (caused by mutation in the EMD gene): If the mother is affected and the father is not, then the male offspring is affected and the female offspring are carriers. X-linked is the most common form, affecting an estimated 1 per 100,000 individuals
- Autosomal dominant (caused by mutation in the LMNA gene): 76% of the individuals affected by Emery-Dreifuss Muscular Dystrophy acquire a new mutation in this LMNA gene with no history of disorder in the family. There are varied case reports that exist for autosomal dominant Emery-Dreifuss Muscular Dystrophy. The current prevalence is unknown
- Autosomal recessive type: Both parents must either be carriers or be affected in order for the child to be affected. Autosomal recessive is the rarest of the three types. There are very few cases worldwide
Who gets Emery-Dreifuss Muscular Dystrophy? (Age and Sex Distribution)
- Emery-Dreifuss Muscular Dystrophy is a rare disorder with an incidence of 1 in 100,000 cases
- Both the autosomal dominant and recessive types of EDMD affect males and females. However, the X-linked type are present in males to a much higher degree
What are the Risk Factors for Emery-Dreifuss Muscular Dystrophy? (Predisposing Factors)
- The only risk factor for Emery-Dreifuss Muscular Dystrophy is a positive family history of the disorder.
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Emery-Dreifuss Muscular Dystrophy? (Etiology)
Emery-Dreifuss Muscular Dystrophy is caused by mutations in the EMD or LMNA gene.
- EMD gene is important for normal skeletal and heart muscle function
- LMNA gene is responsible for the structure of the nucleus (the nucleus contains most of the genetic material of the cell)
What are the Signs and Symptoms of Emery-Dreifuss Muscular Dystrophy?
The signs and symptoms of Emery-Dreifuss Muscular Dystrophy include:
- Contractures in the elbow, spine, and ankle
- Weaknesses in the muscles of the arms and lower legs; later, the face, thigh, and hand muscles may also be involved
- Bradycardia (unusually slow heart rate)
- Arrhythmias (abnormal heart rhythms)
- Heart conduction defects
How is Emery-Dreifuss Muscular Dystrophy Diagnosed?
The diagnosis of Emery-Dreifuss Muscular Dystrophy may involve the following steps:
- A complete evaluation of (family) medical history and a thorough physical exam. During the physical exam, the physician may look for:
- Elbow, Achilles, or neck contractures causing limited joint movements
- Listening to heart sounds with a stethoscope
The following tests will help the healthcare provider diagnose Emery-Dreifuss Muscular Dystrophy
- Electromyography (EMG): To assess the electrical activity in the muscle
- Electrocardiogram (ECG or EKG): To assess the heart patterns and look for abnormal heart rhythms
- CK level test: To measure the amount of creatine kinase in blood; this may usually range from mild levels to about 10 times elevation levels. The higher the creatine kinase level indicates more unusual muscle damage
- Muscle biopsy: It is the examination of muscle under the microscope by a pathologist. Special tests may be performed to confirm the diagnosis
- Prenatal diagnosis is possible when the causative mutation is known in the family
- Molecular genetic tests to detect specific gene mutation
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Emery-Dreifuss Muscular Dystrophy?
Complications associated with Emery-Dreifuss Muscular Dystrophy include:
- Cardiac arrhythmias: Abnormal and irregular heart rhythms
- Sudden cardiac death may occur, if there is no cardiac assistance
- Cardiomyopathy (enlargement of heart)
- Brain clots causing stroke
- Loss of ambulation (movement) with severe contractures
How is Emery-Dreifuss Muscular Dystrophy Treated?
There is no definitive treatment available for Emery-Dreifuss Muscular Dystrophy. However, there are methods to suppress the symptoms or assist the heart, in order to prevent a sudden death.
- Physical therapy and stretching for contractures
- Pacemakers are needed for those with abnormally slow heart rate
- Heart transplants for those with untreatable heart conditions
- Cardioverter-defibrillator can be used for those with abnormal heart rhythms
Other treatment measures may include:
- Achilles surgery can help stabilize shortened ankle joints
- Fixation rods can be used to assist the neck and spine condition
- Antithrombotic drugs to prevent brain blood clots
How can Emery-Dreifuss Muscular Dystrophy be Prevented?
- Currently, there are no specific methods or guidelines to prevent Emery-Dreifuss Muscular Dystrophy, since it is a genetic condition
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
What is the Prognosis of Emery-Dreifuss Muscular Dystrophy? (Outcomes/Resolutions)
- There is no cure and specific treatment for Emery-Dreifuss Muscular Dystrophy
- The prognosis depends on the severity of muscle contractures and the extent of heart involvement
- Some individuals may lose their ability to walk depending on the severity of the Achilles contractures
Additional and Relevant Useful Information for Emery-Dreifuss Muscular Dystrophy:
LMNA genetic changes causing Emery-Dreifuss Muscular Dystrophy are more prevalent than X-linked Emery-Dreifuss Muscular Dystrophy caused by EMD genetic mutations.