CHDH and 22q11.2 deletion syndrome: This phenomenon is exemplified for other CHD genes that are haploinsufficient in humans but require homozygous loss in animal models, including TBX1 (MIM: 602054) (DiGeorge syndrome [DGS] [MIM: 188400]),60,61TBX20 (MIM: 606061),62,63 and GATA4 (MIM: 600576).64