UTRN and neuromuscular disease caused by qualitative or quantitative defects of dystrophin: Utrophin is homologous with dystrophin and upregulated in dystrophin deficiency, potentially serving as a dystrophin surrogate (Matsumura et al. 1992; Tinsley et al. 1998; Cerletti et al. 2003; Nghiem et al. 2013).