Some, such as Duchenne muscular dystrophy and limb girdle muscular dystrophy 2H, are caused by mutations in genes encoding muscle structural proteins (dystrophin and Trim32, respectively) (Hoffman et al. 1987; Frosk et al. 2002), while others, like myotonic dystrophy, are caused by defects in RNA metabolism (reviewed in Wheeler and Thornton 2007; Meola and Cardani 2015). The gene discussed is TRIM32; the disease is myotonic dystrophy.