On the other hand, synaptic transmission becomes more variable with age in the mdx mouse model of DMD (Carlson and Roshek, 2001; Kawabuchi et al., 2011), which could provide one explanation why, despite the consistent lack of dystrophin, mdx skeletal muscle generates less specific force and becomes more susceptible to damage with age (Chan et al., 2007). This evidence concerns the gene DMD and Duchenne muscular dystrophy.