Reappraisal of the incidence rate of Duchenne and Becker muscular dystrophies on the basis of molecular diagnosis.

The incidence rates of Duchenne and Becker muscular dystrophies (X-linked recessive) in a given sample of the Italian population were recalculated using the results of DNA and dystrophin analysis. While the incidence rate of Duchenne muscular dystrophy remained unchanged, the new figure for the incidence of Becker muscular dystrophy (7.2 per 100,000 male live births) was much higher than previously reported, since molecular diagnosis revealed additional cryptic cases, but this incidence is still an underestimate.