The dystrophin protein is an important cytoskeletal protein. It is a rod-shaped protein that localizes in the skeletal and cardiac muscles. Within these cells, dystrophin forms a vital part of a protein complex, called the dystophin-associated protein complex, which connects the cytoskeleton to the extracellular matrix. Proteins associated in this complex include sarcoglycan, dystroglycan, syncoilin, synemin, and others. The major function of this complex is to strengthen the muscle fibers and to protect them from injury as they contract and relax. A small amount of the dystrophin protein is also found in nerve cells. However, here its function is not clearly understood, but suggestions do indicate that it might play a role in maintaining the normal structure and function of synapses.
Defects in the dystrophin protein function are related to some forms of muscular dystrophy, especially the Duchenne (DMD) and Becker (BMD) types. DMD is typically seen in boys as proximal muscle weakness, ultimately resulting in wheelchair confinement. Intellectual impairment is noticed in half of the patients. Similar clinical features are seen in BMD, although in a much more benign form. Dystrophin defects are also associated with X-linked dilated cardiomyopathy, a condition characterized by enlarged and weakened cardiac muscles, resulting in inefficient pumping.