NKX2-5 and coronary artery disorder: We have previously shown that NKX2-5YRDY−A does not affect DNA binding, although it has a strong dominant-negative activity leading to lethal CHD-like phenotypes in high-level heterozygous ES cell chimaeras, and when placed over the null allele creates a phenocopy of NKX2-5 loss-of-function (Elliott et al., 2006).