October 05, 2009
Personalized Medicine and Cancer Genomics
The National Institute of Mental Health (NIMH) talks with Dr. Charis Eng about advances in personalized medicine. As the field of mental health strives to find genetic markers for mental illnesses, we look to the field of cancer research which has made enormous strides in personalized genomic medicine.
Introduction: Welcome to "Speaking of Science." The National Institute of Mental Health presents a series of conversations with innovative researchers working in a wide range of disciplines to pave the way for the prevention, recovery, and cure of mental illness.
Narrator: Hello. This is NIMH Deputy Director Phil Wang. As the mental health field strives to offer patients personalized treatment for mental disorders, we would like to be able to develop genetic markers of disorders like schizophrenia and bipolar disorder that could be used to screen for risk and guide treatment. For a model, we look to fields like cancer genomics, which has already achieved such understanding. For example, thanks to genetic screening, it's now possible for a woman to know her odds of developing breast cancer. I recently spoke with a leader in that field, Dr. Eng.
Dr. Wang: Well it's a pleasure to introduce Dr. Charis Eng. She is the Chair and Founding Director of the Genomic Medicine Institute at the Cleveland Clinic, and a Professor and Vice-Chairman of the Department of Genetics at Case Western Reserve School of Medicine. Dr. Eng got her start at the University of Chicago where she completed her undergraduate degree, as well as her M.D. and Ph.D. at the Pritzker School of Medicine. She then continued her clinical training at Harvard, including an internal medicine residency at the Beth Israel Hospital, as well as a medical oncology fellowships at the Brigham and Women's Hospital and the Dana Farber Cancer Institute. She also completed a fellowship in clinical cancer genetics at the University of Cambridge. Dr. Eng served on the faculty of Harvard Medical School and Ohio State University prior to moving to the Cleveland Clinic. As a founder of the Genomic Medicine Institute, what important advances have you seen in the relatively new field of genomic medicine?
Dr. Eng: Well, while we think genomic medicine or personalized healthcare, and I carefully use the words "personalized healthcare" not "medicine", is new and exciting. It is exciting but it's not new, and some people even say the ancient Egyptians practiced quote "genomic medicine and personalized healthcare." But I think it's safe to day that a/b/o blood typing for safe transfusions, it's the first - or one of the first genomic medicine practices, or genomic based personalized healthcare. Now why has this captured the imagination of both the public and healthcare providers? I think it is because of the tremendous exponential increase in genetic knowledge, genetic technology -- and probably a drop of the price point for ordinary genetic testing has captured our imagination. I mean imagine -- especially in the field of human cancer genetics which is my field, but certainly extrapolable to almost every field of genetics -- I mean imagine being able to find a mutation in the gene, thus making the firm molecular diagnosis. And being able to use that to risk assess. So if someone had a mutation in gene A and gene B, you can say, "well you have an 80% likelihood of developing breast cancer, a 40% likelihood of ovarian cancer. Just to compare, in the general public those numbers are 13% and less than 1%. So you can actually preemptively strike, or perform clinical screening, before the cancers have even started -- even more powerful, with that gene and the mutation. Let's step back. I always tell my patients that a gene is like a multi-volume encyclopedia. Finding an alteration is like finding a typographical error somewhere in an encyclopedia. And for the first person, one has to read every volume of the encyclopedia to find the typographical error. With that single typographical error, on page 5 of volume x, one can go to each of the family members and ask "is that typographical error there?" Just by reading that single sentence. And that is the power of genetic-based predictive testing. Why do you want to do that? If the person does not have the typographical error, the mutation, then the person's at population risk. If the person who is by all means unaffected yet -- has the typographical error, the mutation -- then clinical screening and preemptive strikes may be performed. Such is the power of genomic medicine.
Dr. Wang: What is the role of the genetic counselors at the Genomic Medicine Institute?
Dr. Eng: Yes, that is a very interesting question. Genetic counselors - many people will say: "what are genetic counselors? I never heard of them." And genetic counselors are our partners. We are medical geneticists, and there are so few medical geneticists that genetic counselors are usually Master's level people who've gotten their basic degree in human or molecular genetics, go on two years to genetic counseling school and actually get a Master's of Genetic Counseling. They are board-certifiable. So after one year or two years, they will sit for the boards just like us, and get board certified. I think, in the simplest terms, genetic counselors interpret the very difficult language of medical genetics -- or even translate research to the patient, to the families, and even to the healthcare provider who referred the patient and our family in. So often they will go in and take a rudimentary personal and family history. They will educate them in genetics 101 - so that the patient has a context to understand his or her own family. And then educate them about Mendelian genetics. It's amazing! And then patients absolutely understand. And then they will come out to discuss the case with the MD. And then the team goes back and puts everything into context, both for the patient and his or her family.
Dr. Wang: How is genetic risk assessment linked to conducting in-depth family histories?
Dr. Eng: Yes, I would say the family history is the entre to genetic risk assessment. Very interesting. Two weeks ago I presented at the Centers for Medicare and Medicaid Services in their call to the public for commentary on genetic screening tests. And each of the five speakers, including Dr. Feero from NHGRI - we never talked to each other before, we didn't even know who was speaking -- all of us gave them one message. The family history is the first and best genetic screening tool. And so, in fact, the family history most of the time will clue us into which genes to even begin testing. Because the public says: "Do you know if I've got the breast cancer gene? And we now know that there are eight genes associated with an increased risk of breast cancer. Why differentiate the eight? The eight may have risk of breast cancer but to differing degrees. Some have breast and thyroid - that's P10 which is a gene I discovered. Some have breast and ovarian -- and so on. So it is important to determine which genes. So that actually gives a sort of personalized risk assessment, depending on the gene involved. So it's family history, genes, and then the tests.
Dr. Wang: Has this affected treatment? And how has it maybe affected prevalence rates of disease?
Dr. Eng: I think the best examples are the Jewish diseases - the Tay Sachs and so on - where there is a long enough history to say has it affected the incidence. And Tay Sachs - the incidence of Tay Sachs - has dropped by 90% because of genetic screening, newborn screening, pre-natal screening, in fact.
Dr. Wang: What do you say to people who are afraid of finding our their genetic risks, especially in he case where you don't have a treatment, say in Huntington's Disease.
Dr. Eng: Yes, that's a tough one. Well, studying this phenomena, it' not just Cleveland Clinic, it's all over. Many patients will come and say "I was so frightened to come. My doctor would say I had to go and see the geneticist, or a genetic counselor. I thought a genetic counselor was like a psych counselor. But I'm so happy I came because with all this information, I am empowered. I can do something." Now, for the cases of Huntington's and Alzheimer's. At least for now, where you can't do anything -- and this is where genetic counseling is vital -- they must understand and be at peace with what they decide. Most patients who want to know will say: "I know we can't do anything, but I want to know because if I have it, I want to set my affairs in order." So everyone has a personal reason. And I think so long as they and the genetic counselor have had a very good session, and they understand why they're doing it, it's fine.
Dr. Wang: Dr. Eng I'd like to thank you, and it's been a pleasure talking to you.
Dr. Eng: The pleasure's mine. Thank you.