As recent data have suggested that Cx43 lateralization contributes to DMD arrhythmogenesis in mdx mice (Gonzalez et al., 2015), we performed whole-mount immunostaining with a Cx43 antibody to examine the distribution of Cx43 gap junctions in working cardiomyocytes and in Purkinje fibers. The gene discussed is GJA1; the disease is Duchenne muscular dystrophy.