DMD and Duchenne muscular dystrophy: It affects 1 in 3800–6300 males, and there are an estimated 15,000 patients with the disease in the USA.2,3 There is no approved therapy that addresses the underlying cause of DMD.4,5 In ∽13% of boys with nonsense mutation DMD (nmDMD, which represents ∽1700 boys in the USA and ∽2400 boys in Europe), the causative defect in the dystrophin gene is a nonsense mutation that truncates dystrophin protein production by introducing a premature stop codon into dystrophin mRNA.6–8