DMD and Duchenne muscular dystrophy: However, systemic restoration of dystrophin expression in vivo will be important for therapeutic correction in DMD patients and this has proven considerably more challenging in animal models with currently tested AO chemistries (i.e. 2′OmePS, 2′-O-methyl phosphorothioate RNA; PMO, phosphorodiamidate morpholino and PNA, peptide nucleic acid) as previously reported [10], [11], [12], [13], [14], [15], though the former two AO chemistries are currently in phase IIa/IIb clinical trials.