BMP4 and atrial septal defect: Moreover, when each of the congenital heart defect subgroups ASD and VSD was compared to the normal hearts, similar fold expression values were found regarding BMP2 mRNA (p = 0.72, p = 0.33, respectively, t-test) and BMP4 mRNA (p = 1.00, p = 0.99, respectively, t-test).