Genetic and Chromosomal Factors
Most congenital heart defects arise from a combination of genetic susceptibility and environmental exposure that disrupts normal heart development during the first 8 weeks of fetal life. Chromosomal conditions are among the most clearly established causes: Down syndrome (trisomy 21) is associated with atrioventricular canal defects and ventricular septal defects in approximately 40–50% of affected individuals; Turner syndrome is associated with bicuspid aortic valve and coarctation of the aorta; and 22q11.2 deletion (DiGeorge syndrome) is associated with conotruncal defects such as tetralogy of Fallot and interrupted aortic arch. Single-gene mutations, including those in genes encoding cardiac transcription factors and structural proteins, account for a smaller proportion of cases.
Environmental and Maternal Factors
Environmental contributors to congenital heart disease include poorly controlled maternal diabetes (which substantially increases the risk of several cardiac defects), maternal rubella infection in the first trimester, certain teratogenic medications (such as thalidomide, lithium, some anticonvulsants, and isotretinoin), excessive alcohol consumption, and environmental exposures. For the majority of families, however, no specific cause is identified, and CHD is best understood as a multifactorial condition. Genetic counseling and fetal echocardiography are recommended for families with a personal or family history of CHD, or where a chromosomal condition has been identified in the fetus.
Reviewed by Dr. Pradeepkumar Charla, MD, MBA, FAAP, FACC
Pediatric & Adult Congenital Cardiologist — Congenital Heart Compass Medical PLLC
Last reviewed:
Medical disclaimer: This content is for educational purposes only and is not a substitute for individualized medical advice, diagnosis, or treatment. Always consult a qualified cardiologist for decisions about your congenital heart disease care.