As far as he knew, Paul had no family history of the disease. But after checking, Paul learned that several aunts and uncles had died of colon cancer at an early age. Cancers arise from a multistep process, which involves the interplay of multiple changes, or mutations, in several different genes, in combination with environmental factors such as diet or lifestyle. In the most common, noninherited forms of cancer, the genetic changes are acquired after birth. But individuals who have an hereditary risk for cancer are born with one altered gene - in other words, they are born one step into the cancer process.
Women also face a markedly increased risk of uterine and ovarian cancer.
Finally, in the spring of 1993, using tools emerging from the Human Genome Project , an international team tracked the gene to a region of chromosome 2. Seven months later, two teams zeroed in on the culprit. Together, these genes account for most cases of this inherited cancer. These discoveries offer a view of how the Human Genome Project is likely to transform medicine by opening up new approaches to prevention. The earliest beneficiaries will be those families facing a very high risk of colon cancer.