In answering this question, it is important to consider a number of important points. Firstly, muscular dystrophy is not a single disease but rather a group of conditions caused by faults in many hundreds of different genes. Muscular dystrophies may vary dramatically in severity, age of onset and prognosis. A person with muscular dystrophy typically has faults in one gene. The exact faults may vary in different individuals, even within the same gene.
Secondly, gene therapy is a technique that modifies a person’s genes to treat or cure disease. Gene therapies can work by several mechanisms, including replacing a disease-causing gene with a healthy copy of the gene, inactivating a disease-causing gene that is not functioning properly, or introducing a new or modified gene into the body to help treat a disease. There are currently many different approaches to achieving these aims. In addition, the majority of therapies that are being developed are aimed at treating a specific condition with faults in a single gene. In some cases the therapy may be aimed at only a specific type of fault in one gene or even at only one fault.
Gene therapies potentially offer some advantages over more standard therapies in that they may need to be given only once or a few times in an individual’s lifetime. However, few gene therapies are available that have been through completed clinical trials. Because few patients are eligible for any particular therapy, and their development costs are large, gene therapies are likely to be extremely expensive options. In addition, some may need to be given by using invasive techniques, e.g. into the brain if brain tissue is affected. Additionally, for muscular dystrophies, by the time patients manifest disease they may have lost a significant amount of muscle tissue. Further, development of muscle occurs in utero, and new muscle cells do not really develop after birth. Therapies are thus more likely currently to slow disease than reverse it or cure it.