Coronary artery disease (CAD) is a narrowing of the small blood vessels that supply blood and oxygen to the heart. CAD is the most common form of heart disease in the Western world and is one of the leading causes of death in the United States. In addition to lifestyle and environmental factors which are major aetiologic determinants, there is considerable familial clustering of the disease indicating a genetic component in its causation. Although the total genetic contribution to CAD risk can be quantified, the determination of the size and number of contributing effects is impossible...