Improved diagnosis of Duchenne/Becker muscular dystrophy.

Molecular genetics has revolutionized the way one should con- sider a patient with muscular dystrophy. The purpose of this Perspectives article is to set the parameters by which physi- cians may judge their neuromuscular patients in the context of recent advances in the understanding of both genetic and bio- chemical aspects of muscular dystrophy. We will first review some of the progress that has occurred over the past 5 years. This will illustrate how advances at the basic science level have led directly to powerful new diagnostic tests and, hence, to a new "molecular definition" of Duchenne and Becker muscu- lar dystrophies (DMD and BMD).' After discussing the strengths and weaknesses and appropriate use of these tests, we will end with specific examples of their use in a clinical setting. We hope this review will aid in the rapid transition of these tests from the research laboratory to routine clinical use.