The present invention relates to the use of an inhibitor of histone deacetylase for preparing a drug for the treatment or prevention of a disease resulting from the deficiency of an adult gene in an individual by the re-expression of the homologous fetal gene. The invention concerns in particular the treatment of dystrophies such as Duchenne's dystrophy or Becker's dystrophy in which the defective adult gene is the dystrophin gene and the homologous fetal gene is the utrophin gene.