The purpose of this review is to analyze the clinical applications of
a remarkable series of advances made in molecular genetics, primarily
with regard to Becker muscular dystrophy. A new classification is requ
ired to clarify such syndromes as Duchenne and Becker muscular dystrop
hy. Dystrophinopathies can be seen in patients with early onset and a
severe course (Duchenne muscular dystrophy), patients with later onset
and milder weakness (Becker muscular dystrophy), patients with myalgi
a and cramp syndrome, and patients with dilated cardiomyopathies. Dyst
rophin testing in muscle is the most sensitive test for identification
of dystrophinopathy patients, although gene deletion studies can make
the diagnosis in most cases.