Until recently, genetic testing for medical purposes has brought to mind inherited changes (mutations) in so-called BRCA genes, which increase risks for breast, ovarian and other cancers.
Now: Genetic testing is being increasingly used to give advance warning of elevated risk for dozens of potential health problems. Unlike tests that help identify an existing medical condition, predictive genetic testing is done to determine whether a person carries one or more genetic mutations that make him/her more likely to develop a particular health problem than someone without the mutations.
An early warning of potential problems allows the patient and doctor to identify preventive measures to reduce risk for the disease. Getting a positive test result, however, does not typically mean that the person will definitely develop cancer or another condition linked to a genetic mutation that shows up through testing. There are many factors that influence health and disease, including your environment, diet and health behaviors.
What the Tests Can Tell You
Genetic testing can give an early warning if you’re at elevated risk for…
Cardiovascular disease. Genetic testing can identify dozens of mutations, including SCN5A and MYH7, that are linked to increased risk for a range of potentially fatal heart issues, such as an abnormal heart rhythm (arryhythmia) or cardiomyopathy, a disease of the heart muscle. Heart-related mutations are more likely to occur in families that have a history of early-onset cardiac failure and death.
High cholesterol. If you’re diagnosed with high cholesterol, your doctor likely will recommend lifestyle changes, such as a diet that focuses on foods high in fiber and healthy fats, weight loss and exercise. But if high cholesterol is caused by a genetic condition called familial hypercholesterolemia (FH), more aggressive treatment is needed, such as regular use of a statin drug. Increased risk for FH is linked to mutations in such genes as PCSK9 and LDLR. In families that have hypercholesterolemia, high cholesterol is typically identified at very young ages, including in children. These mutations also may be associated with a family history of heart disease and heart attacks at young ages.
Parkinson’s and Alzheimer’s diseases. About 10% to 15% of Parkinson’s cases can be attributed to mutations of GBA and LRRK2 genes, among others. With Alzheimer’s, a mutation in the apolipoprotein E gene, known as APOE e4, is among those that increase risk. Your risk of developing late-onset Alzheimer’s is around three times higher than the average person’s if you’re among the 25% of people who carry one copy of APOE e4…or 12 times higher if you inherited APOE e4 from both your parents.
Chronic kidney disease. Genetic tests can identify mutations in genes such as PKD1 that are associated with increased risk for kidney failure. This testing can be a potential lifesaver, since kidney failure often goes undetected until its late stages, and transplants are frequently done with donor kidneys from relatives. Signs of genetic kidney disease include kidney failure in more than one related family member and disease at younger ages than typically observed.
Cancer. Recent research has confirmed how common genetic mutations are in people who develop cancer. When more than 3,000 cancer patients were tested, one in eight were found to have an inherited genetic mutation that significantly increased their odds of developing the disease.
While most people are aware of genetic testing for BRCA mutations (mentioned earlier), it’s not widely known that these mutations also can occur in men, increasing their lifetime risk not only for breast cancer, which is rare in men, but also for skin, pancreatic, digestive tract, colorectal and prostate cancers. BRCA mutations can be passed on by women or men to their daughters and sons. These mutations are commonly found in those of Ashkenazi Jewish descent.
Should You Get Tested?
Even though genetic testing has many benefits, it’s not something that everyone needs. Speak to your doctor or a genetic counselor about this type of testing if you have…
More than one family member affected by a medical condition with a possible genetic component, such as the conditions listed above. The odds are especially high that inherited gene mutations are to blame if one or more of these relatives experienced the condition at a younger age than it normally occurs, such as heart problems or cancer in their 20s. Sometimes having only one family member with a medical condition may be enough to trigger suspicion of a genetic disease if onset of that condition was unusually early. In such cases, it is best to first have the person who has been diagnosed with the condition tested, if possible.
A medical problem or symptoms that your doctors haven’t been able to diagnose. Many rare diseases have an underlying genetic cause. This is particularly true when multiple systems in the body are impacted.
A diagnosed medical condition that could benefit from treatment that genetic testing may identify. This could include people with certain types of cancer, high cholesterol or kidney failure.
Costs of Genetic Testing
If your doctor orders a genetic test, it generally is covered by insurance or Medicare as long as the results could be “clinically useful,” meaning that a positive result would lead to preventive measures or treatment. Check with your insurer before testing to confirm whether it will be covered. If your insurance won’t pay, the out-of-pocket cost varies from hundreds of dollars for a “focused” test to thousands for an “exome” or “whole genome” test (see box on page four). Warning: Testing for Parkinson’s and Alzheimer’s risk often is not covered, because the results of these tests do not point to a specific treatment or improve the odds of survival.
One downside of genetic testing: It could potentially make it more expensive or difficult to obtain life, disability or long-term-care (LTC) insurance. Insurers sometimes ask applicants if they
have had genetic testing done and/or whether they are aware of any reason why they might be at elevated risk for medical problems uncovered by genetic testing. Unlike life, disability or LTC insurers, however, health insurance companies and employers are legally barred by federal law from asking about genetic testing.
Helpful: Genetic counselors can assist you in finding the right genetic test for your medical and family history and in interpreting the results. If your hospital or medical center does not have a genetic counselor on staff, check FindAGenetic Counselor.org. Your health insurance may cover the cost of working with a genetic counselor, but check first.