The purpose of this study is to discover genes that may cause Coronary Artery Disease (CAD) or Arteriovenous Malformation (AVM). Many human diseases are inherited or passed from parent to child in families. These diseases occur because of damage to a gene(s), the genetic material that is also called DNA. Scientists can now use modern molecular techniques to locate and to find certain genes within the DNA (genetic material) of a person, and to follow their inheritance in a family. To find these disease-causing genes requires studies of many affected with the disease and their family members. The purpose of this study is to locate and to find the genes for coronary artery disease (CAD) which occurs when one or more of the arteries that carry oxygen-rich blood from your heart to the rest of your body develop blockages; or, arteriovenous malformation (AVM) which causes abnormal vascular connections between arteries and veins, particularly near the heart. Findings of the genes causing CAD and AVM will have far-reaching effect on the diagnosis, treatment, and prevention of coronary artery disease and arteriovenous malformation. These studies will lead to possible genetic diagnosis, early detection of persons at risk for developing CAD or AVM (even in the absence of symptoms), development of effective drugs, more rational and specific therapeutic interventions, treatments and ultimately, prevention of coronary heart disease. Approximately 3-5 years are required to find one human disease gene.