,33,34,35,36,37 The mdx mouse model of DMD houses a point mutation in exon 23 of the dystrophin gene which causes a loss of the full-length dystrophin isoform (Dp427), however, the expression of the four shorter isoforms (Dp260, Dp140, Dp116 and Dp71) are still apparent through differential internal promotors within the gene.38 The gene discussed is DMD; the disease is Duchenne muscular dystrophy.