DMPK and Myotonia: Interestingly, model mice acutely overexpressing a normal-length DMPK 3′ UTR mRNA reproduced cardinal features of myotonic dystrophy, including myotonia, cardiac conduction abnormalities, histopathology and RNA splicing defects in the absence of detectable nuclear inclusions (Storbeck et al., 2004; O'Cochlain et al., 2004; Mahadevan et al., 2006).