Wednesday, July 10, 2013

How Much Do Your Genes Matter To Your Health?

One of the biggest misconceptions that people have about their health is the role that genetics play.  The role of genetics in health is one of my favorite topics and I have lectured about it extensively.  (See my two part video on YouTube on The Role of Genetics in Longevity and How To Live to 100 at http://www.youtube.com/watch?v=dcmX4UFAyB4)

"My mother lived to 93," patients may say to me.  "I expect to live just as long."

Other patients have said something like "My father died from a heart attack at 73 and I'm afraid I will die early too."

So here's the good and bad news for any of you who share similar thoughts, good or bad.  For the most part, you are not your parents. That doesn't mean that you don't share genetic traits with them. It's simply means that given the approximately 25,000 genes now identified by human genomic researchers, the probability that you have the same exact genes and mutations as your parents, siblings, and other close relatives is highly unlikely, if not impossible.

The whole gene area is now under intense study. Hardly a week goes by without a new gene-disease connection being reported.  With names like BRCA-1, BRAF and PKCS9, the scientific community is abuzz with the significance of these findings. They should be as it's a big deal.

For illustrative purposes, I'd like to share three of these gene-disease connections.

There was a lot of recent press about Angelina Jolie's decision to undergo a double radical mastectomy due to her having the BRCA-1 gene mutation. What many people do not know is why this mutation is connected to breast cancer. The mutation itself does not cause the breast cancer. Why? The answer requires knowledge of the role of a normal BRCA-1 gene, which is to repair damaged DNA.

Our DNA is constantly being damaged, both as a result of environmental factors (the study of which is called Epigenetics) like radiation and harmful chemical exposures and by believed random occurrences during cell division.  These mutations, by their nature, can create cancerous cells.  These fledgling cancers, however, are usually either destroyed by our functional immune system or the cells' DNA damage is repaired by genes that have that function.

A normal functioning BRCA-1 is one of the genes that aids in this repair. Those with one form of the mutation (there is a second form that over-repairs DNA including that of cancer cells destroyed by chemotherapy, thereby allowing the cancer to defeat the chemo) are unable to repair DNA damage that then leads to full blown breast cancer.  In other words, people with this mutation can't easily avoid developing breast cancer because they are more vulnerable to cells growing into amass..

Not everyone with this gene develops breast cancer because the cancer development still depends on the degree to which their DNA is being damaged by lifestyle and other factors. (A good argument for living a healthy lifestyle.) Nevertheless, with a less than perfectly functioning immune defense system, they are at significantly increased risk.

(As an aside, in regards to the BRCA-1 gene, it turns out that my relative who is struggling against metastatic kidney cancer was found to have the BRC-1 gene mutation in the cancer.  As a result, the treating oncologist decided to try a novel approach to this cancer that included treating it with a chemotherapeutic agent typically reserved for breast cancer. Amazingly, if not miraculously, the previously relentlessly spreading tumor responded and actually shrank a little bit. Although the jury is still out as to long term consequences, the news was unexpected and encouraging.)

Researchers have long known that aspirin therapy appears to correlate with lower rates of colon cancer. Recently, they discovered that it only works in people who do not have a BRAF gene mutation. Given that aspirin can cause serious side effects like bleeding and ulcers in certain people, this newly discovered information will help doctors decide who is most likely to fully benefit from aspirin therapy as the test for this gene becomes more accessible.

Today's New York Times has an article describing the race between major pharmaceutical companies to develop a new treatment for lowering cholesterol. Based on research of a gene labelled PKCS9, scientists discovered that people with such a gene mutation  have lower levels of LDL, the bad cholesterol. Among two known cases where each individual inherited the mutation from both parents, the LDL reached remarkably low levels and the two individuals had no evidence whatsoever of heart disease. The pharma companies are fast at work at developing drugs to mimic the affect of the PKCS9 gene mutation.

This coming Fall, I will be giving a keynote address at the FAU Lifelong Learning Center on "Miracle Cures, Magical Pills, and Quick Fixes, Welcome to 22nd Century Medicine." My talk will center on some of the most promising scientific areas of research. Undoubtedly, the role of genes will factor heavily in the most significant advances to our understanding of disease and both its treatment and prevention over the next century.

At the moment, you can't pick your genes any more than you can pick your parents, but understanding the interaction of your genes and your lifestyle can lead to some good lifestyle decisions that may help you stay healthy.  As I like to say to my patients, "Don't obsess about your genes, but don't ignore them either." In other words, what you do to your genes matters as much as what genes you have. Stay thirsty for knowledge my friends.

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