House Call: Genetic testing can boost health awareness
Shortly after my diagnosis with breast cancer in 2010, I completed genetic testing to determine if I carried the mutated BRCA 1 or 2 gene that increases risk of breast and other cancers. I was tested because of my age, the aggressiveness of my tumor and my family history. Not everyone who has breast cancer needs or should have this kind of testing. This is an example of genetic testing done on adults.
Scientists think each of us has about 30,000 to 35,000 genes. Genes are the sections of DNA in our cells that provide instructions to make proteins in our bodies. They are responsible for determining everything from hair color to our risk of certain diseases.
We know about 2,000 genes are connected to specific conditions. These conditions may be caused by not having a gene, having too many copies of a gene or by having a mutated gene that disrupts the gene’s protein-making instructions. As more gene/protein connections are better understood, it will be possible to understand how the disruption of their functions relates to disease and ill health.
In the future, genetic testing may help determine what medications will work best for individuals, which chemotherapies are best for which cancer and who is at specific risk for myriad diseases. Because our present knowledge of genes is incomplete, genetic testing needs to be approached with reasonable expectations.
Testing positive for a gene or genes linked to disease usually means you have an increased risk of developing the disease compared to the general population, not that you will definitely develop the disease. There are only a handful of conditions, such as Huntington’s disease, where testing positive means you will develop the disease.
On the other hand, testing negative for a gene does not mean you will never develop the disease. About 75 percent of the women who develop breast cancer do not have the BRCA gene mutations linked to an increased risk of breast cancer. I am one of them – my test was negative.
So why would you want to get genetic testing as an adult? The most common reason is a pattern of disease in your family. You may want to see if you have the gene (or genes) affecting your risk. In some cases lifestyle changes, surgery or other interventions may counter your increased risk. In other cases, an increased risk of a disease may mean you and your health care provider should be on the lookout for specific signs or symptoms of the disease. Or you should consider more frequent testing for the condition than is recommended for the general population.
Belonging to an ethnic group at higher risk for a disease is another reason to consider testing. Or perhaps you want to know if you are a carrier for a condition before having children. For example, in cystic fibrosis, a child needs to get one copy of the gene from each parent.
If you are considering genetic testing, write down your family health history. Then make an appointment to discuss it with your health care provider. He or she can refer you to a genetics service to discuss all of the above issues with a genetic counselor.
If it makes sense to have a genetic test for a condition, be sure to discuss what you will do if the test is abnormal. Sometimes it is a good idea to put off testing until you need to know or until there are treatment options.
Genetic services can be found at the National Society of Genetic Counselors website, www.nsgc.org. An international Genetics Clinic directory can be found at the GeneTests website, www.genetests.org.