It describes Duchenne MD as the most common type of MD, almost exclusively affecting males at a rate of about 1 in 5,000 boys, and eight rarer types of MD that are categorized by age of onset, muscles affected, disease progression, severity of symptoms, and health complications. The author describes how physical examination, muscle biopsy, medical imaging, and genetic testing is used to diagnose MD He further explains the underlying causes of the various types of MD as mutations in genes that encode proteins needed for the development, function, maintenance, and replacement of muscle cells and illustrates patterns by which they are inherited.

There is no treatment that can reverse the progressive deterioration of muscles caused by MD, but the book offers insight into drug treatments and physical therapies that help maintain muscle strength and reduce health complications. It concludes with explanations of promising new ways to treat or perhaps cure MD, including experimental drugs, stem cell therapy, and gene therapy.