PRRX1 and Arrhythmia: This is consistent with the observed longer atrial APD in Tbx5RE(int)KO mice compared to controls, which may predispose to increased arrhythmia inducibility, as seen in mice harboring the pathogenic TBX5-G125R variant or Prrx1 enhancer deletion (Bosada et al., 2021; van Ouwerkerk et al., 2022).