The DMD gene and therapeutic approaches to restore dystrophin

Duchenne muscular dystrophy (DMD) is a severe X-linked disease characterized by progressive muscle weakness. It is caused by a variety of DMD gene pathogenic variations (large deletions or duplications, and small mutations) which leads to the absence or to a decreased amount of dystrophin protein. The allelic Becker muscular dystrophy is characterized by later onset and milder muscle involvement, and other rarer phenotypes might also be associated, such as dilated cardiomyopathy, cognitive impairment, and other neurological signs. Following the identification of the genetic cause and the disease pathophysiology, innovative personalized therapies emerged. These can be categorized into two main groups: (1) therapies aiming at the restoration of dystrophin at the sarcolemma; (2) therapeutics dealing with secondary consequences of dystrophin deficiency. In this review we provide an overview about DMD genotype-phenotype correlation, and on main approaches to restore dystrophin as stop codon read-through, exon skipping, vector-mediated gene therapy, and genome-editing strategies, some of these are based on approved orphan drugs. Finally, we present the clinical potential of novel strategies combining therapies to correct the genetic defect and other approaches, targeting secondary downstream pathological cascade due to dystrophin deficiency.