Understanding the cause of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is an X-linked recessive degenerative disorder of the muscle. The normal gene codes for a protein named dystrophin, which is approximately $500$‍ kDa in size. It is a component of muscle, present in rather low amounts. In DMD patients, there is a deletion mutation in the dystrophin gene that leads to either a defective form of dystrophin or a lack of dystrophin completely. Utilizing an experiment where DNA probes, made from the normal dystrophin sequence, were hybridized to DNA from normal individuals and to DNA from DMD patients, scientists were able to identify sequences that correspond to the region of DNA that contains the deletions characteristic of DMD. The deletions occur at different locations in each patient, suggesting that they occur de novo. The most severe and common deletion is located in the center of the locus. The sequence of the deletion in the coding strand was determined to be: $5$‍’—GCCATAGAGCGA—$3$‍’.