In conclusion, our siRNAs were safe and showed significant downregulation of Alk4 in both nondystrophic and dystrophic muscles, including the diaphragm, which is the most affected muscle in DMD patients, thus making treatment of siRNAs with similar chemical modifications and lipid conjugates for targets involved in the secondary pathology of DMD interesting. The gene discussed is ACVR1B; the disease is Duchenne muscular dystrophy.