GJA1 and rhizomelic chondrodysplasia punctata: Thus, Cx43‐deficient mice exhibit cardiac conduction abnormalities such as an increased duration of the QRS interval in the electrocardiogram.15, 16 ECG changes consistent with cardiac conduction abnormalities (first degree heart block, right bundle branch block) have also been found in RCDP patients.5 Interestingly, Pls are particularly enriched in the sarcolemma of cardiac myocytes.17 Accordingly, one aim of the current study was to investigate whether Gnpat KO mice exhibit prolonged electrical conduction in the heart as would be expected from the reported reduction of Cx43 levels.13