BY AMBER SMITH
If you’re intrigued by offers of direct-to-consumer medical genetic testing, Robert Roger Lebel, MD, director of medical genetics at Upstate, offers something to consider.
Let’s say you come from a family with many members who have had breast cancer, and you’re interested in knowing your risk. Many genes are associated with breast cancer. The genetic testing company you select may focus on a couple of different mutations in the most well-known of those genes.
When your results show you do not have an increased risk for the breast cancer associated with that particular mutation on the BRCA gene, “You may think that you have investigated the question and have your answer, when you really don’t,” Lebel says.
“If you talked with a board-certified genetic counselor about this, he or she might tell you that there are actually 50 different genes that could be of interest in regard to your family’s presentation. You were tested for two different things in one gene. You were not tested for thousands of things in dozens of genes.”
Genetic home testing can be useful, Lebel says, in the case of positive findings.
The tests cannot tell you that you will develop a particular disease. “They can identify factors that tell you that your risk is higher than that of a member of the general population.”
So, if your results show an increased risk for breast cancer, ovarian cancer and pancreatic cancer, “then you could talk to somebody with expertise about how to use this knowledge to minimize your long-term risk,” he says.
“It would allow you to talk to your physician about how to watch for early signs.”
What about genealogy?
Ancestry.com, 23andMe and others offer tests using saliva samples that explore deep ancestry.
“They won’t tell you the name of your great-grandfather, but they will tell you whether your great-, great-, great- greats came from Northern Africa or Eastern Europe or Southeast Asia,” says Lebel.
How do the tests work?
We all have genes or DNA sequences on chromosomes known as markers. “Some of those markers are very common in certain parts of the world and very uncommon in other parts,” Lebel explains, “so that they are able to state with some statistical clarity where those markers would have come from.
“If you’ve always said that you were of mixed European ancestry, German, Swedish, Czech and Hungarian, and you really want to know in detail whether you have, say, 3 percent of your genome from East Asia — which you might, because the Hungarian part might have descended from Genghis Khan — well, you can find out.”
This article appears in the fall 2018 issue of Upstate Health magazine. Click here to hear Robert Roger Lebel, MD, discuss home genetic testing in a podcast/radio interview with Upstate’s “HealthLink on Air.”