The utility of intermediate traits as end points. This greatly simplified schematic assumes there are 10 genes contributing equally to the clinical end point (ie, 10% each, faint dashed lines). Another level of complexity to the pathophysiology is superimposed by including 5 intermediate traits, each contributing 20% to the clinical outcome. In this example, genes 1 and 2 have a much larger effect on platelet reactivity (50%) than on the clinical end point (10%). Of course, environmental factors also play a major role in these end points (not shown).