HAND1 and congenital heart disease: Studies have shown that congenital heart disease is associated with chromosomal abnormalities, monogenic gene defects, and polygene defects, and genetic loci found to be associated with the development of congenital heart disease include NKX2.5, GATA4, TBX1, TBX5, FOX1, Lefty, SMAD3, GDF1, HAND1, and HAND2 [28, 29].