While small CNVs (< 1 Mb) (e.g., GATA4, 22q11.2) are linked to CHD (e.g., VSD, conotruncal defects), their low penetrance necessitates additional genetic (e.g., NKX2-5 SNVs) or environmental (e.g., maternal diabetes) factors to cause CHD. Here, NKX2-5 is linked to ventricular septal defect.