Decades ago, mass-scale epidemiologic studies were undertaken to accurately describe the prevalence of congenital heart disease and associated malformations, and to identify inheritance patterns, teratogenic influence and aetiologic underpinnings. Despite phenomenal breakthroughs in molecular diagnosis of congenital heart disease, original population-based studies for detailed knowledge of prevalence, associated malformations, and appropriate patient and family counselling remain invaluable to the armamentarium and knowledge base of paediatric cardiologists. No modern-era studies have supplanted the importance of the Baltimore-Washington Infant Study undertaken from 1981 to 1989. In this article, we reprise the findings of the Baltimore-Washington Infant Study in tetralogy of Fallot, as well as to review current molecular diagnosis.
