Other transgenic mice with tetracycline-inducible heart-specific expression of human mutant DMPK mRNA with 960 repeats have been used to study the cardiac pathogenesis in DM1 [27], whereas the mouse model most commonly used to study DM1 pathology in the CNS is the DMSXL mouse, with more than 1000 CTGs in the human DM1 locus (45 Kb), muscle defects and high mortality, although with mild missplicing [28]. The gene discussed is DMPK; the disease is myotonic dystrophy type 1.