Genetic predisposition doesn’t have to mean predestination. If your family history suggests you carry a dangerous gene, you can be placed on high-alert surveillance. Men whose mothers had family-linked breast cancer may, for example, be at risk of colon and pancreatic cancer. Awareness of this should lead to more frequent testing and earlier treatment. Women who learn of a history of ovarian and breast cancer before menopause might choose to get the test for the BRCA1 or BRCA2 gene. Here are some guidelines to help you understand your own genetic background:
First, trace your roots. To fill in the major branches of your medical tree, draw on your family’s best oral historians. Then check their memories against medical records, autopsy reports and death certificates. Even old family pictures can help. Milunsky remembers a photograph of a patient’s grandmother, whose droopy eyelids confirmed a type of muscular dystrophy (a dominant gene).
Be skeptical, though. “The more distant the history in general, the less relevant it is to the current generation,” says Vivian Weinblatt, president of the National Society of Genetic Counselors. And the less reliable. Relatives may say that Grandma died of a “female” cancer, but not whether the cancer was ovarian (which can be inherited) or cervical (more likely caused by a sexually transmitted disease).
Once you’ve done the digging, share the information. “The updated family tree is an important document that should be kept by multiple family members,” says Milunsky. The tree can help relatives with planning children, for example. Knowing that family members carry the gene for Huntington’s (an adult-onset, incurable neurodegenerative disease) may make a couple decide to adopt children rather than bear them or to use donor eggs or sperm. “Even if there isn’t a cure, there still might be lifestyle decisions,” says Weinblatt.
Some risks are ethnic. Six percent of Ashkenazic Jews carry a gene mutation that can lead to colon cancer. One in 12 African-Americans carries a mutation for sickle-cell anemia. And as many as 5 percent of Caucasians carry a defect in the factor V (for “five”) leiden gene that predisposes them to develop blood clots in the leg.
Finally, lifestyle choices influence vulnerability. While you can’t change your genes, you can change your habits. If many family members have died of arterial aging, you should consider more-scrupulous exercise habits, a healthier diet and taking an aspirin a day–to keep your arteries free of clots and decrease your risk of the small-scale strokes associated with memory loss. “If you escape one of the childhood diseases, then by the time you’re 50, 80 percent of how well and how long you live is under your control,” says gerontologist Michael Roizen, author of “Real Age: Are You As Young As You Can Be?” Genetic detective work can increase that control. You don’t have to be Sherlock Holmes to figure that out.
