How are duchennes muscular dystrophy and myotonic muscular dystrophy different?

Amount of Dystrophin: The two conditions differ in their severity, age of onset, and rate of progression. Mutations in the dmd gene cause duchenne and becker forms of muscular dystrophy (dmd and bmd, respectively). Mutations that lead to an abnormal version of dystrophin that retains some function usually cause bmd, while mutations that prevent the production of any functional dystrophin causes dmd.