A common genetic variation on chromosome 9p21 is linked to a substantial increase in risk for heart attack. Researchers found individuals with the variation have a 1.64-fold greater risk of suffering a heart attack (myocardial infarction) and a 2.02-fold greater risk of suffering a heart attack early in life than those without the variation. Approximately 21 percent of individuals of European descent carry two copies of the genetic variation (one from each parent).