Dr. Stephen Tapscott studies how genes are turned on and off and how this activity goes awry in certain diseases. He focuses on the activity of certain “master” genes that control the development of muscle and nerve cells. He is a leader in understanding how the normal process of cell development is altered in two diseases: muscular dystrophy, a class of inherited diseases in which muscles weaken and atrophy over time; and rhabdomyosarcoma, a type of cancer that arises from muscle cells. Dr. Tapscott’s team made a breakthrough in unlocking the molecular secrets behind one of the most common forms of muscular dystrophy, facioscapulohumeral dystrophy, or FSHD. Dr. Tapscott found that in people with FSHD, proteins normally present in early development are erroneously activated in muscle cells, which prevents muscle-cell regeneration and possibly triggers a damaging immune attack against the muscles.