Discoveries

DNA Testing, Decoded

John Lee, MS

Photo by Al Cuizon

A program manager and genetic counselor at the Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute, John Lee, MS, discusses game-changing advances related to genes, the proactive power of DNA testing—and why consumers may be buying bad science.

Q: How did genetic counseling pop up on your career radar—are you from a medical family?

A: My mom is a nurse and my sister’s a family doctor, so I guess I am. But I discovered genetic counseling when I took a genetics class at Rutgers University. Genetic counseling is a good fit because I really enjoy interacting with patients. I also like keeping my science mind sharp—genetic analysis and staying current on constantly evolving genetic-testing techniques are good ways to do that.

Another reason this career proved to be a super good choice is because that’s how I met my wife, who’s also a genetic counselor. As part of her training, she shadowed some counselors—including me—a couple of times. And here we are.

Q: Who should consider genetic testing?

A: People with a personal or family history of specific diseases should consider it to determine whether they’re at risk for developing the disease or passing on a predisposition to their children. I also recommend genetic testing for certain races or ethnic groups who have a higher incidence of particular conditions. Sickle cell disease, for example, occurs most frequently in African Americans, and Tay-Sachs disease is more prevalent among individuals of Ashkenazi (Eastern and Central European) Jewish ancestry.

Q: Should some people be evaluated by a genetic counselor as part of their cancer care?

A: Patients diagnosed with cancer at younger ages than is typical, or who have multiple family members with the same type of cancer, could benefit from a genetic evaluation. Patients interested in knowing whether their cancer is hereditary should request one, too. Genetic assessment also can help patients determine what treatments may be most effective, their risk of developing other cancers and whether family members have an increased cancer risk.

Q: What can genetic tests determine?

A: Genetic testing can reveal really important information that someone might not otherwise know. A husband and wife I recently worked with are a good example. Their daughter was diagnosed with breast cancer in her 30s, which is younger than average, so they requested genetic testing. Cancer runs in the husband’s side of the family and his relatives carry genetic mutations related to breast cancer, so we assumed he would test positive for a mutation. He didn’t, but his wife did. As a result, she went immediately from bystander to patient. She’s since had surgery to reduce her ovarian cancer risk.

Our assessments determine whether a patient is a carrier of a hereditary cancer syndrome and whether they’re likely to develop a certain type of cancer themselves. The tests also inform medical follow-up. For example, if a woman tests positive for BRCA1 or BRCA2, which are inherited gene mutations responsible for about 5-10% of breast cancers and roughly 15% of ovarian cancers, we’d recommend additional breast screening and discuss preventive surgical options.



Q: How has the field advanced in recent years?

A: This is a very exciting time in the world of genetics, with the most significant advance being next-generation sequencing. Before this technology existed, it was expensive and time-consuming to identify the genetic information carried in specific genes. Now we can simultaneously sequence millions of genes rapidly—and at relatively low cost. This has resulted in uncovering hundreds of previously unknown genetic causes of cancer and many other diseases.

Q: Direct-to-consumer genetic testing companies like 23andMe and AncestryDNA do big business—more than 26 million people have purchased at-home DNA test kits. What is the science on these products?

A: When I first started seeing commercials for these testing services, on one hand, I thought it was cool that genetic testing was being introduced to a mass audience. On the other hand, I wondered what type of information people were going to receive and if the tests could provide actionable results.

The bottom line is: Consumers should be cautious. These home tests don’t provide deep-dive, comprehensive assessments that can inform important medical decisions. And the results are questionable because these companies tend to do surface-level genetic analyses. For example, when 23andMe assesses a woman’s breast cancer risk, it only tests for three gene mutations. Not only are there thousands of identified breast cancer mutations, but the three it tests for are most commonly found in women of Ashkenazi Jewish ancestry, so testing women outside of that group is largely unproductive. That’s not good science—though 23andMe does recommend that users speak to a genetic counselor who can help explain the findings and discuss next steps. I hope consumers see that and follow up.

John Lee, MS

Licensed Certified Genetic Counselor
Program Manager and Genetic Counselor, Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute


When John Lee isn’t helping patients reduce their risk of certain cancers, you’re likely to find him:

PLAYING TENNIS or watching his favorite pro, Roger Federer, play.

LISTENING TO MUSIC, particularly the Red Hot Chili Peppers’ “Soul to Squeeze.”

TRAVELING Lee’s travel itinerary includes trips to his hometown of Chatham Township, New Jersey, but he also enjoys new adventures. Recent journeys include Japan, South Korea and Alaska. In April, Lee and his wife traveled to Massachusetts, where she ran in the Boston Marathon while he cheered her on.

This interview has been condensed and edited.