Duchenne muscular dystrophy (DMD) is inherited in an X-linked recessive pattern and occurs at an incidence of 1 in 3500 male births, which means that it is a so-called "orphan" or rare disease (frequency < 1/2000). Yet it is one of the most frequent myopathies and is observed in all populations. We review here the spectacular advances made in our understanding of this disease since the identification in 1986 of the responsible gene. This gene encodes a subsar-colemmal component of the cytoskeleton, dystrophin. We consider the impact of this discovery on molecular diagnosis at the protein and DNA levels. Despite the time that has passed since, the discovery of the gene has not led to any treatment, and we review the therapeutic prospect.