We performed echocardiography on the hearts of the mice 7, 14, and 28 days post-TAC and observed that the fractional shortening and left ventricular internal diameter (LVID) was significantly worse only at the early days post-TAC (Fig. 4e-g) in Col1a2-CreERT: R26RtdTomato: p53CKO mice compared to murine hearts with intact p53. The gene discussed is TP53; the disease is persistent truncus arteriosus.