It is an inherited disorder which is due to the mutation in the dystrophin gene which codes for the protein dystrophin.Dystrophin is a rod shaped protein preset in the cytoplasm.It connects the muscle fiber to the outside environment.Its deficiency has bees identified as the root cause of the myopathies called as muscular dystrophyMuscular dystrophy refers to the group of hereditary muscle disease.A milder form of such dystrophies is beckar's muscular dystrophy.Nine diseases are included in the dystrophy as:Duchenne, Becker, limb girdle, congenital, facioscapulohumeral, myotonic, oculopharyngeal, distal, and Emery-Dreifuss.Becker's muscular dystrophy is a  X inked recessive condition.
Becker's muscular dystrophy results in slowly progressive disability, and patients eventually use a cane or wheelchair. Death can occur from age 40 but some patients enjoy a nearly normal lifespan.

It is purely due to the change in the genome of individual.i.e it is purely a hereditary disease. It is recessive X- linked and the gene is located on the X chromosome.If a female is a carrier and the male is normal the, she has 25%male will be affected by this disease and 25% will remain unaffected.
Females will remain unaffected but 25% are carrier.3-6 in 100,000 male births are affected by the this disease.As the muscle is gradually damaged then to fulfill its requirement it produces more source of energy which is Phosphocreatine.Pcr and ADP combines in the presence of the creatine phosphokinase and provides energy to the muscles.Hence its level get elevated in the muscular dystrophy, myocardial infarction.
During the onset of the muscular dystrophy,certain proteins like dystrophin lead to the tearing of the muscle fibres and influx of more ca ion in the mitochondrial membrane.This causes the swelling of the Mitochondria and hence finally the cell death occur.

There is no known prevention.
 

As this is a genetic diseases, genetic counselling is necessary for the parents who have gene of muscular dystrophy and they want a normal child.