Genetic testing

Issue: BCMJ, vol. 60, No. 5, June 2018, Page 237 Editorials

“Hey Doc, what are you going to do to help me? I’m at risk for obesity, gout, diabetes, gallstones, heart disease, and kidney disease.”

“Bob, despite the fact that obesity is already more of a fact than a risk for you, what are you talking about?”

“I did one of those home DNA tests, and my printout said I’m at higher risk, so I’m worried.”

“And you weren’t worried when I explained last month that 300 lbs on your 5′6″ frame increased your chances of heart disease and other adverse conditions?”

We live in interesting times. Patients now have access to home genetic testing, and for less than $200 these at-home kits allow individuals to research their ancestry. In addition, these companies provide genetic reports on disease predisposition and carrier states. One could argue that this is a wonderful technological advance because patients can now take control of their lives and mitigate risks. However, this information is being given without genetic counseling to people who might not be ready to hear it or understand what information they are actually getting. A genetic mutation doesn’t actually mean you will get the disease; nor does it explain the other complex factors that go into disease risk. 

Probably the most well-known genetic test is for mutation of the BCRA1 and BCRA2 genes, which if positive significantly increase a woman’s risk for breast and ovarian cancer. But how can a patient make an informed decision about future treatments to mitigate risk without an expert guiding them through this maze of gene expression and penetrance? Also, these tests check for some mutations but not all, and if negative might convey a false sense of security and lead individuals to stop potentially lifesaving screening. 

I did some online research, and it appears that not all companies have the same level of credibility. Some make unsubstantiated claims that seem a little farfetched. One company will test for 31 conditions, 53 carrier states, 12 drug-response genes, 6 wellness traits, 11 other traits, and 11 addictions. Your genetics will even be matched to dietary and exercise advice along with supplements and skin products that the company conveniently sells. Some of the listed traits did make me smile, particularly ear-wax type (who cares), digit ratio (can’t you just look at them?), and newborn hair amount (didn’t anyone take baby photos?). The drug-response item also caused me to pause. Apparently, your genes reveal how you will metabolize proton pump inhibitors, respond to hepatitis C treatment, and how sensitive you will be to warfarin and clopidogrel (I admit this would be valuable information to have). As for addiction testing, if the result is negative, should an individual use alcohol, cocaine, and heroin without a care in the world? 

Lastly, the wellness tests listed include alcohol flush, caffeine metabolism, depth of sleep, lactose intolerance, and muscle performance. If you are predisposed to being a black-coffee-swilling, red-faced alcoholic-insomniac with weak muscles, should you just give up?

As technology continues to advance, physicians will definitely face new challenges in processing the wealth of ever-expanding testing and knowledge. I believe my DNA is heavily sprinkled with the stalling-while-I-Google gene, so hopefully I will be okay. Good luck to the rest of you. 

David R. Richardson, MD. Genetic testing. BCMJ, Vol. 60, No. 5, June, 2018, Page(s) 237 - Editorials.

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