ETS1 and congenital heart disease: However, after testing, the authors concluded that the critical region for congenital heart defects is only 1.2 Mb, including the ETS-1, FLI-1, KCNJ1, KCNJ5, P53AIP1, and RICS genes, ETS-1 being one of the genes expressed in rat embryos during early cardiac development.11