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. 2014 Mar 18;124(4):1844–1852. doi: 10.1172/JCI73140

Figure 3. EnhA and EnhB are necessary for Scn5a cardiac expression.

Figure 3

(A) Modified murine BAC RP23-198L19 with LacZ inserted into the endogenous Scn5a translational start site. (B–F) Stable BAC transgenic lines, shown in whole-mount and cross-section histology; arrows indicate AV bundle (blue) and distal bundle branches (red). Pie charts show the distribution of LacZ expression in each genotype class. All studies were performed at 12 weeks of age; the number of independent transgenic lines examined is indicated (each analyzed in triplicate). (B) The WT enhancer demonstrated robust CCS and myocardial expression. (C) EnhA deletion eliminated proximal CCS and myocardial expression. (D) EnhB deletion eliminated distal CCS and myocardial expression. (E) Deletion of both enhancers eliminated CCS and myocardial expression entirely. (F) The minor allele at rs6801957 markedly altered Scn5a-LacZ expression, which was either entirely absent or absent from the atrioventricular bundle and confined to the distal ventricular septum in the majority of cases.