Duchenne Muscular Dystrophy
Duchenne muscular dystrophy is probably the best known myopathy so much so in fact that often the more general term muscular dystrophy is used when referring to Duchenne muscular dystrophy. The disease is X-linked recessive. The gene for Duchenne muscular dystrophy is located at the short arm of the X chromosome.
Although the cause of the disease is unknown, there are three theories about its pathogenesis, namely a myogenic or membrane theory, a vascular theory and a neurogenic theory.
Some infant patients are silent and move very little while still in the cradle. In most cases though the first clinical signs appear when the child shows delayed motor development. He is late sitting, standing and walking and when he does begin to walk, he often falls. The parents notice how difficult it is for the child to get up again once it has fallen. As many of he patients will have flat feet as well, arch supports are often prescribed. The time between the first consultation and establishing the correct diagnosis can vary from 0-8 years, with an average of 3 years. By the time the patient's mean age is 6 years.
Signs of the diseases
The child stands with its abdomen forward and has hyperlordosis Well developed or even hypertrophic calf muscles- Pseudo hypertrophy Child has flat feet Genu recurvata can also be observed Wadding gait when walking Gowers sign
Neurological examination shows more weakness in the pelvic girdle and leg musculature than in the muscles of the shoulder girdles. Many patient will continue to walk and climb stairs reasonably well until they are 8 years old. By about the age of 11 years most patients require a wheelchair. Sometimes a serious kyphoscoliosis develops. Cardiomyopathy occurs in over 80% of the patients About half the patients have low IQ.
In view of the far-reaching consequences of the disease for the patient and the entire family it is very important that the diagnosis is established with as much certainty as possible. The following examinations are necessary to achieve this:
- Determination of serum Creatine kinase
- Muscle biopsy
The identification of carriers of this X-linked recessive disease plays an important role in genetic counseling. Duchenne carriers are classified as follows:
- Definite carriers- mothers of a son with DMD with another affected relative-brother, maternal uncle, nephew(sister side) grandson or other male relative in the female line
- Probable carriers-mothers with two or more sons with DMD who have no other male relatives in the female line with the disease
- Possible carriers- mothers who have only one son with DMD and no other affected male relatives.
No drug is known to halt or even improve the disease process. On the other hand close support to the parents/ child; regular monitoring, and long term physiotherapy, as well as orthopedic aids are all important for the patient's well being and quality of life. There are no agreed surgical guidelines; but there are basically two approaches: one aims to keep the patient on his feet for as long as possible by surgical means, the other attempts to avoid surgery as much as possible and accepts the disadvantage of the patient requiring a wheelchair at an early stage.
- Stem cell therapy
- Gene therapy