f you could take a genetic test to find out if you had an elevated risk of a deadly disease, would you? Should you? And if you did, how would you deal with the results?
Those are questions that genetic counselors and patient advocates deal with all the time. A new poll from STAT and the Harvard T.H. Chan School of Public Health found that about half of respondents would consider such a test if it would signal their risk of cancer or Alzheimer’s disease.
By Susan Brown: When women call Susan G. Komen’s Breast Care Helpline with questions about genetic testing, we first need to understand why they are seeking this information. Some women want to know about genetic testing in general, or about direct-to-consumer genetic tests, such as those provided by 23andMe and other companies. We don’t recommend direct-to-consumer tests because it is difficult to know how to interpret the results or what to do with the information. The results of any genetic test should be interpreted by a trained health care provider or genetic counselor.
For women calling the helpline with questions about genetic testing for breast cancer, part of our job is to provide reassurance, especially for those who feel they need to get tested right away. Although it may feel like it, it isn’t an emergency situation. They have time to learn more about genetic testing from a trusted health care provider and then consider whether genetic testing is right for them.
In the United States, only a minority of breast cancers — between 5 percent and 10 percent — are caused by inherited genetic mutations. The most common ones are in the BRCA1 and BRCA2 genes. They occur in about 1 in 400 to 1 in 800 Americans, but are more common in certain populations. Genetic testing for these mutations makes sense for some people. (A list of who should consider testing is available on our website.)
Before a person embarks on genetic testing, we encourage them to begin working with a genetic counselor. A counselor takes a family and personal history. This information could suggest the presence of a genetic mutation in the family and can help with the decision to go forward with genetic testing. A counselor can also help a person think about the possible impact of possible results before testing occurs, and then interpret test results if the decision is made to get tested.
Susan Brown, RN, is managing director, health and mission program education, at Susan G. Komen.
By George Yohrling: Huntington’s disease is caused by a mutation in a single gene. Anyone with that faulty gene will eventually develop, and likely die from, Huntington’s disease. An individual with the gene has a 50-50 chance of passing it to each of his or her children.
The Huntington’s Disease Society of America doesn’t encourage or discourage genetic testing for at-risk individuals. It’s a very personal decision. The majority of at-risk people don’t want to know, especially since there is currently no cure for Huntington’s disease. Only about 10 to 15 percent of people choose to be tested.
Gene therapy is one of the hottest topics in Huntington’s disease research today. A company called Ionis Pharmaceuticals has recently begun a Phase 1 clinical trial of a drug that “silences” the Huntington’s gene. This reduces the body’s production of the protein that causes the symptoms of the disease. Other companies are close to testing other gene therapy options. Although this research represents a huge step forward, it’s important not to let hope and expectation run ahead of reality.
Lately we have been fielding a flood of questions about gene editing. The technology known as CRISPR-Cas9, which can replace one gene with another, theoretically holds great promise for Huntington’s and other genetic diseases. Will it be the next “great cure” for them? That remains to be seen. We try to counsel individuals with Huntington’s disease and their family members that the use of CRISPR is years away from being used to treat Huntington’s disease. Today it should be seen as a laboratory tool that needs to be developed, discussed, and ethically explored.
George Yohrling, PhD, is senior director for mission and scientific affairs for the Huntington’s Disease Society of America.