A disrupted compartment boundary underlies abnormal cardiac patterning and congenital heart defects (opens in new tab)

Failure of septation of the interventricular septum (IVS) is the most common congenital heart defect, but mechanisms for patterning the IVS are largely unknown. Here we show that a Tbx5+/Mef2cAHF+ progenitor lineage forms a compartment boundary bisecting the IVS. This coordinated population originates at a first and second heart field interface. Ablation of Tbx5+/Mef2cAHF+ progenitors causes IVS disorganization, right ventricular hypoplasia and mixing of IVS lineages. Reduced dosage of the co...