Using an unbiased systems-based screen, we demonstrate the cardiac transcription factor TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival as mice heterozygous for both Tbx20 and Casz1 die post-natally as a result of dilated cardiomyopathy (DCM).We have used quantitative proteomic approaches to define the molecular pathways mis-regulated in Tbx20 and Casz1 mice and thus, are associated with DCM. Using an unbiased systems-based screen, we demonstrate the cardiac transcription factor TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival as mice heterozygous for both Tbx20 and Casz1 die post-natally as a result of dilated cardiomyopathy (DCM).We have used quantitative proteomic approaches to define the molecular pathways mis-regulated in Tbx20 and Casz1 mice and thus, are associated with DCM.