DMD mutations involving shorter Dp isoforms and associated with a BMD phenotype also result in cognitive/behavioural abnormalities.20 Most of our current knowledge about the functions of dystrophin isoforms in the brain comes from studies of DMD patients or animal models of DMD, where the underlying genetic mutation disrupts the expression of one or more dystrophin isoforms. This evidence concerns the gene DMD and Becker muscular dystrophy.