Such testing does hold promise, says David Flannery, medical director of the American College of Medical Genetics and Genomics. But he cautions that widespread genetic testing is still unwarranted. Here’s advice on several genetic tests that make sense for at least some people, as well as some that aren’t yet ready for prime time:
Heart disease
It’s now possible to check for two inherited heart conditions: familial hypercholesterolemia (very high cholesterol) and hypertrophic cardiomyopathy, a thickening of the heart muscle, says Donna Arnett, a cardiac epidemiologist at the University of Kentucky College of Public Health in Lexington.
When to consider testing: For familial hypercholesterolemia, testing can make sense if you have a family history of high cholesterol and an LDL reading of more than 190 mg/dL confirmed on two occasions. For that condition and for hypertrophic cardiomyopathy, testing might also be worthwhile if a first-degree relative (parent, sibling or child) has the disease.
How it can help: One study found that only 20 percent of people with familial hypercholesterolemia who were treated with cholesterol-lowering statins developed heart disease over 12.5 years of follow-up, compared with slightly less than 40 percent of those not treated. And if testing reveals cardiomyopathy, it’s wise to have an electrocardiogram and echocardiogram every three to five years, depending on your age. If any thickening of heart muscle is found, your doctor may monitor you more closely or prescribe medications such as beta blockers.
When to skip it: Nix testing if you have no family history of either disease or, in the case of familial hypercholesterolemia, if your total cholesterol is less than 250 mg/dL or your LDL is less than 190 mg/dL.
Breast cancer
Mutations to two genes — BRCA1 and BRCA2 — cause up to 10 percent of breast cancers and 15 percent of ovarian cancers. These mutations have also been linked to melanoma and pancreatic and prostate cancers.
When to consider testing: Testing might be useful if you have a personal or family history of breast or ovarian cancer, or a relative known to have a BRCA variant, or if you have an Ashkenazi Jewish heritage plus a close relative with breast or ovarian cancer; some BRCA variants are more common in that group.
How it can help: Women with either gene mutation can have more-frequent breast cancer screening. They could also consider the breast-cancer-prevention drug tamoxifen or even preventive mastectomy or the surgical removal of the ovaries.
When to skip it: Say no if you don’t have a strong family history of breast cancer. “Patients are still frequently sent to me who aren’t good candidates,” Flannery says, such as women whose family history “turns out to be just two cases on opposite sides of the family.”
Colon cancer
About 3 to 5 percent of colon cancers stem from an inherited condition called Lynch syndrome (hereditary nonpolyposis colorectal cancer), which also increases the risk of ovarian, pancreatic and stomach cancers.
When to consider testing: You might want testing if you have a blood relative with colon or uterine cancer before age 50, or more than two people on the same side of your family diagnosed with colon, endometrial, ovarian, pancreatic or stomach cancer, says Mary Freivogel, president-elect of the National Society of Genetic Counselors.
How it can help: People with Lynch syndrome have up to an 80 percent higher risk of developing colon cancer. So it’s a good idea for them to have an annual colonoscopy to remove potentially precancerous polyps, instead of doing so every three to five years, as is usually recommended for people with polyps.
When to skip it: If you don’t have the hereditary red flags noted above, there’s little reason to have the testing.
Two tests to skip
The following tests are sometimes recommended by doctors, even though research shows they are inaccurate or have no effect on treatment options:
Alzheimer’s. One genetic test screens for an early-onset form of the disease, another for a gene, APOE, that increases the risk of developing it later in life.
Why skip it: Early-onset Alzheimer’s accounts for less than 1 percent of dementia cases. And the test for the APOE gene isn’t very accurate: Although about 15 percent of Caucasians and 25 percent of African Americans have the variant, that doesn’t mean they’ll develop the disease. Last, “there’s no way to prevent Alzheimer’s, so you can’t do anything differently to reduce risk, and in fact knowing the gene is present can cause anxiety or discrimination in obtaining long-term-care insurance,” says Heather Snyder, senior director of medical and scientific operations at the Alzheimer’s Association.
Eye vitamins. Some doctors say that testing people with age-related macular degeneration (AMD) for certain gene variants can help determine whether the patients should take a supplement with only zinc and copper or one that also has vitamins C and E, lutein and zeaxanthin.
Why skip it: The study behind that recommendation was funded by the very lab that performs the gene test. And it was refuted by a major 2015 National Eye Institute study. “Genetic tests for AMD have no proven benefit for treatment for the patient being tested,” says study lead author Emily Chew, deputy clinical director at the National Eye Institute.
Copyright 2016. Consumers Union of United States Inc.
For further guidance, go to ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.
Source: Washington Post
