Duchenne muscular dystrophy is a malignant muscle disease that is based on a genetic defect on the X chromosome, which means that the disease can only occur in male offspring. The symptoms already appear in infancy in the form of weaknesses in the pelvic and thigh muscles. It always ends fatally in early adulthood due to the breakdown of the heart and lung muscles.
What is Duchenne muscular dystrophy?
Duchenne muscular dystrophy (DMD) is a progressive muscle weakness that is based on a genetic defect on the “male” X chromosome. Because the gene defect is on the X chromosome, the disease can only occur in male family members. See electronicsmatter for Leukoplakia Definition.
For these, however, it is homozygous because the gene on whose mutation the disease is based only occurs once and cannot be compensated for by a second gene – as is usually the case with a diploid chromosome set. This means that male offspring with the presence of the genetic defect will definitely develop DMD.
DMD becomes apparent at an early age between the ages of one and six through muscle weakness and muscle breakdown in the pelvic and leg muscles. The disease itself is triggered by a synthesis disorder of the protein dystrophin. Dystrophin is an important and functionally necessary component of the membrane that surrounds the muscle fibers (sarcolemma). DMD is the most common form of all known muscular dystrophies.
The so-called DMD gene, which is responsible for coding the protein dystrophin, is located on the X chromosome. With 2.5 million base pairs, it is the largest known gene in the human genome and is therefore susceptible to mutations, which usually completely prevent the synthesis of dystrophin.
The mutation of the DMD gene can involve the loss (deletion) of a section (several base pairs), a duplication or a point mutation in which only a single nucleobase is affected. The mutations trigger various forms of muscle weakness, of which Duchenne muscular dystrophy is by far the most common manifestation.
It is noteworthy that about a third of boys who develop DMD are caused by a de novo mutation and are not inherited from their mothers. This explains why DMD is not decreasing significantly in the frequency of its occurrence.
Symptoms, Ailments & Signs
Duchenne muscular dystrophy (DMD) manifests itself in the first years of life and begins in the pelvic girdle area. The toddlers have trouble walking, run unsteadily, trip and fall more often. You are unable to run fast. Due to the weakened thigh muscles, they are also unable to stand up on their own, but support themselves with their hands on their thighs when standing up.
This characteristic symptom is also known as Gower’s sign. People with Duchenne muscular dystrophy (DMD) show an increase in connective and fatty tissue, especially in the calf area. As a result, her calves appear unusually strong.
In medical jargon, the thickened calves are called gnome calves. Furthermore, in patients with Duchenne muscular dystrophy (DMD), pointed feet and a pronounced curvature of the spine in the lumbar region can be observed.
Duchenne muscular dystrophy (DMD) progresses rapidly, so that the majority of patients are dependent on a wheelchair and full-time care before the age of 12. In the advanced stage of the disease, a weakness in the respiratory muscles leads to breathing difficulties. Furthermore, those affected have reduced reflexes and suffer from sensory disturbances. About a third of the patients also have an intellectual disability.
Diagnosis & course of disease
If the initial suspicion is confirmed, neurological examinations and functional tests of the muscles are indicated. Imaging methods such as MRI and ultrasound can also provide further information. An increased level of the muscle enzyme creatine kinase can often be detected in the blood. Ultimate certainty is created by genetic diagnostics, which also allows muscular dystrophy to be assigned to one of the known manifestations.
The course of DMD is progressive. From the age of 5 to 7, those affected can usually no longer get up from a sitting or lying position without outside help and can no longer climb stairs. The muscle wasting leads to deformation of the joints and storage of fatty tissue in the muscles as a replacement for the muscle tissue. As a rule, the children from the 10th to 12th year are dependent on a wheelchair. Life expectancy is around 40 years, although an earlier death before the onset of puberty cannot always be prevented.
Duchenne muscular dystrophy usually leads to death. Death occurs at a very young age. Parents and relatives in particular are affected by the illness from strong psychological complaints and upsets. Due to the disease itself, the patients suffer from a very weakened musculature.
This weakening takes place throughout the body, so that internal organs and the heart are also weakened. Eventually cardiac death occurs. Likewise, normal activities are difficult for the person concerned to carry out and the patients suffer from a very low resilience. It is not uncommon for patients to be dependent on the help of other people in everyday life.
Joints and muscles are often deformed and Duchenne muscular dystrophy leads to significant restrictions in movement. This disease can also lead to psychological complaints and thus significantly reduce the patient’s quality of life. There is no treatment for Duchenne muscular dystrophy.
Those affected are dependent on various therapies in order to increase life expectancy, which, however, is greatly reduced. However, no particular complications arise during treatment.
When should you go to the doctor?
In the event of muscle strength disorders, reduced physical performance or muscle tension, a doctor should be consulted. If there are irregularities in the development and growth process in direct comparison to peers, a visit to the doctor is advisable. If you have low resilience or tire quickly, we recommend consulting a doctor. Deformations of the physique, a poor posture of the upper body or a general incorrect loading of the skeletal system must be examined and treated. A curvature of the spine is characteristic of Duchenne muscular dystrophy and should be immediately discussed with a doctor.
A doctor is required in the event of breathing disorders, shortness of breath or interruptions in breathing. Immediate action is required in the event of an acute impairment of breathing or a lack of oxygen. Signs of this are blue discoloration of the lips and fingers, loss of consciousness and internal weakness. In severe cases, an emergency service must be alerted. Until his arrival, the person concerned needs mouth-to-mouth resuscitation. If the affected person suffers from sensory or perception disorders of the skin, this is a sign of an existing irregularity. It should be clarified so that treatment can alleviate the symptoms. In the event of an abnormality in mental potential, an alleged intellectual disability or a learning disability, a visit to the doctor is advisable.
Treatment & Therapy
To date, AMD is not curable. All attempts at gene therapy have so far been unsuccessful and probably failed because of the body’s own immune system. Drugs have been under development or even in experimental testing for a number of years, which are intended to mitigate the effects of the gene defect on dystrophin synthesis, so that the body can synthesize dystrophin again – at least to a limited extent.
One drug currently in clinical trials is eteplirsen, also known as AVI-4658. Another drug in the experimental phase is ataluren. In the presence of so-called nonsense mutations, which lead to a termination of the transcription of the base sequences due to so-called stop codons, ataluren should be able to prevent the transcription from being terminated. If successful, this means the body would be able to synthesize dystrophin again, thereby halting muscular dystrophy.
The therapies currently used are aimed at relieving the symptoms and also include life-prolonging measures, but have no effect on the actual cause of the disease. The catalog of measures for combating symptoms consists of a mix of medical care, physiotherapy and ergotherapy as well as care and psychological support for the patients and their families. As the disease progresses, breathing aids via oxygen masks are necessary. In later phases, an incision in the trachea (tracheostomy) is usually necessary in order to be able to carry out active ventilation.
Outlook & Forecast
There is currently no cure for Duchenne muscular dystrophy. The disease is characterized by a characteristic course and usually has the same prognosis for all those affected. Slight muscle weaknesses in the legs become noticeable between the ages of three and five. The atrophy of the thigh and pelvic muscles then progresses steadily, with connective and fatty tissue then replacing the gradually dwindling muscle tissue. Later, the muscles of the shoulders and arms are also affected by muscular dystrophy.
Between the ages of five and seven, the affected children need constant help to get up from a lying or sitting position. Many of the affected children with Duchenne muscular dystrophy completely lose the ability to walk by the age of 12, which means that they are no longer able to do without a wheelchair. In the further course of the disease, those affected can initially still take care of themselves, but to a limited extent. In most cases, however, patients are then dependent on full care from family members from the age of 18 onwards.
Finally, Duchenne muscular dystrophy also affects the respiratory muscles as well as the heart muscle of those affected, which reduces their life expectancy. As the disease progresses, it almost always leads to death from suffocation or heart failure.
Since AMD muscular dystrophy is caused by a genetic defect, direct preventive measures that could offer protection against the onset of the disease are not known. However, an early diagnosis, if possible in the first or second year of life, helps to combat and delay the symptoms with a wide range of therapeutic measures. In addition to nutrition and supplying the body with minerals, amino acids, vitamins, enzymes and trace elements, targeted physiotherapy is important in order to maintain muscle function for as long as possible.
In the case of Duchenne muscular dystrophy, the options for direct follow-up care are usually significantly limited or, in some cases, are not even available to the patient. For this reason, the person affected should ideally consult a doctor at an early stage in order to avoid the occurrence of other symptoms or complications.
It cannot heal itself, so a visit to a doctor is usually necessary. Most patients are dependent on the help and care of their own families in everyday life. In doing so, those affected must be relieved, whereby in general exertion or stressful and physical activities are to be avoided.
Psychological support is often important to prevent depression and other mental disorders from occurring. Furthermore, in the case of Duchenne muscular dystrophy, physiotherapy measures are also necessary in order to alleviate and limit the symptoms. Many of the exercises can also be repeated at home to further alleviate the symptoms.
Further follow-up measures are usually not available to those affected by this disease. Duchenne muscular dystrophy may also reduce the life expectancy of the patient.
You can do that yourself
For those living with Duchenne muscular dystrophy, assistive devices are very important. They increase the quality of life, make everyday life easier and support participation in society. It is all the more important to be well informed about which aids are suitable and what options for care are available. In the late ambulatory and non-ambulatory phases, additional aids may be needed to manage everyday situations such as eating and drinking and personal hygiene.
Trade fairs for medical aids, where manufacturers present their products, are excellent for finding out more. There you can get a good overview of the tools that can be used. In addition, contact with other families affected by Duchenne muscular dystrophy or other muscle diseases can also be helpful. The German Society for Muscle Diseases offers a comprehensive range of advice and supports parents in establishing contact with other affected people.
If the affected child has not been dependent on a wheelchair for a long time, wheelchair training can be helpful at the beginning, in which the correct handling of the wheelchair is learned.
The elasticity of the muscles and the preservation of joint mobility are important prerequisites for maintaining the functionality of the limbs for as long as possible. In many cases, daily stretching exercises with family support are essential in addition to physical therapy.