Musclar Dystrophy

The official name of the gene that is affected in Duchene Muscular Dystrophy is Dystrophin and is often called the ‘DMD gene’.
It is the largest known gene in the human genome and spans a massive 2.5 million base pairs and is composed of 79 exons.
Its cytogenetic location is Xp21.2, meaning it is found on the short arm of the X chromosome at position 21.2

Since its discovery, there has been more than 1000 different mutations that occur within the Dystrophin gene that result in the condition.
Duchene Muscular Dystrophy is a result of a genetic abnormality, and in two thirds of cases an affected male inherits the mutation from his mother, who carries an altered copy of the DMD gene.
In the other one-third of cases, Duchene Muscular Dystrophy is a result of spontaneous mutations that are not inherited, but occur after birth.
The majority of associated mutations are deletions which account for 65% of all cases. Duplications and other small point mutations account for a much smaller ratio of the condition representing around 10% each.
It is thought that the size and position of the deletions in the DMD gene often do not correlate with the clinical phenotype observed, meaning that a large deletion doesn’t nessecry mean a more severe case of muscular dystrophy.

As deletion mutations are the primary cause of the condition, I thought it would be best to focus on this type mutation.
The vast majority of large deletions detected in Muscular Dystrophy, cluster around two ‘hot spots’, which are between exons 2-20 and exons 45-55.
As rumbi has just described the structure of the dystrophin protein is essential in its functionality of binding muscle to its surrounding extracellular matrix. Mutations in the DMD gene dramatically affect the dystrophin protein and ability to carry out its function
Mutations in Exons 2-20 affect the N-terminus in the actin-binding site of molecule, this can be seen as the green region of the diagram and generally result in dystrophin...