Once I had brains, and a heart also; so having tried them both, I should much rather have a heart.
The Tin Woodsman of Oz
Congenital heart defects, describing those present at birth, are the most common birth defects - affecting almost 1 percent of all babies born - and are the leading cause of birth defect-related deaths.
Congenital heart defects include a variety of malformations of the heart or its major blood vessels that are present at birth. These defects may obstruct or cause blood to flow through the heart in an abnormal pattern (hypertrophic cardiomyopathy, ventricular Septal Defect, tetrology of fallot) or affect heart rhythm (long QT syndrome).
While the cause of most congenital heart defects is unknown, some heart malformations do have a clear genetic link such as from large chromosome aberrations such as 22q11.2 deletion syndrome, and single gene defects as seen in syndromes such as Noonan syndrome. In addition, a vast and diverse number of genetic syndromes also present with heart defects as one of the symptoms.