written by Emily Bucklely, editor in chief
There are many different types of genetic tests. Results can be used to diagnose disease, identify gene changes responsible for already-diagnosed diseases, determine the severity of a disease, guide physicians in medication and treatment decisions, identify risks of developing a disease, identify gene changes that could be passed on to children, and to screen babies for specific treatable conditions.
According to David Kirkman, M.D., OB/GYN at the Cache Valley Women’s Center, the science of genetic testing is being improved rapidly, and although genetic test results can be difficult to understand, specialists can determine what the results could mean for you and your blood relatives.
Diagnostic testing is used to diagnose or confirm diagnoses of specific diseases. Diagnostic tests can be performed before birth or at any time throughout life. The results of a diagnostic test may help you make choices about how to treat or manage your health.
Predictive testing can determine whether a person could develop a genetic disorder before symptoms appear. These tests can benefit people who have a family history of a genetic disorder and aid in making decisions about frequency and types of screenings to have done.
“Recommendations about what genetic tests would be beneficial for you are often based on your family history,” Dr. Kirkman said. For example, testing for BRCA mutations, which can cause breast cancer, is recommended for anyone with two second-degree relatives or one first-degree relative who was diagnosed with breast cancer prior to going through menopause.”
According to The National Cancer Institute, about 12 percent of women in the general population will develop breast cancer sometime during their lives. Conversely, it is estimated that about 72 percent of women who inherit a harmful BRCA1 mutation and about 69 percent of women who inherit a harmful BRCA2 mutation will develop breast cancer by age 80.
“Knowing your risk will help you and your doctor know what to watch for and help catch things sooner, which dramatically helps in the ability to treat disease,” Dr. Kirkman said.
Carrier testing is used to find people who ‘carry’ a copy of a gene mutation. Carriers may show no signs, but when two copies are present a genetic disorder occurs. Carriers can pass on the mutation to their children, who may develop the disease or become carriers themselves.
“If you’ve experienced symptoms, like cardiac arrest caused by longed QT syndrome, for example, carrier gene testing can make you aware of the risks and help you and your blood relatives make lifestyle choices,” Dr. Kirkman said.
Prenatal testing is offered during pregnancy to help identify fetuses that have certain diseases.
“Many people don’t understand the value of these tests, because they say the results wouldn’t change anything,” Dr. Kirkman said. “But mothers can make proactive decisions on treatment, where to deliver their baby, or the quality of life they will be able to provide their child, based on the results. At the very least you can heighten awareness and catch things earlier.”
Newborn screenings are used to test babies shortly after birth to see if they have certain diseases, like phenylketonuria or congenital hypothyroidism, known to cause problems with health and development.
Pharmacogenomic testing gives information about how certain medicines are processed by an individual’s body. This type of testing can help your physician choose medicines that work best with your genetic makeup.
“Research on this kind of testing is developing quickly and can help prevent a lot of trial and error when it comes to deciding what medications will best help patients,” Dr. Kirkman said.
“There are a lot of tests for a lot of different things,” Dr. Kirkman said. “It is important to know our family history and talk to your doc. Information is power and can be very helpful — from treatment and screening planning to lifestyle choices and avoidances.”