UTRN and Duchenne muscular dystrophy: For example, previous research has shown that SERCA pump function is more severely impaired in the mdx/utrophin double knockout (dko) mouse (Schneider et al., 2013; Voit et al., 2017)—a severe DMD mouse model where both dystrophin and its functional homolog utrophin are completely absent (Deconinck et al., 1997; Grady et al., 1997).