Functional impairments resulted from GATA6 mutations. Activation of atrial natriuretic factor–luciferase reporter in HEK-293 cells by GATA6 wild-type (WT), mutant D404Y, or mutant E460X, alone or in combination, demonstrated significantly decreased transactivational activity by mutant proteins. Experiments were performed in triplicate, and mean and standard deviations are shown. ** and * represent p<0.001 and p<0.005, respectively, when compared with wild-type GATA6.