Adam’s Journal
Here’s a question from a reader:
I got a half-price holiday special offer for complete genome sequencing. It said the test would identify up to 15,000 early warning signs and potential health risks for $280. Do these kinds of tests provide useful information?
Chris Lee
Dr. Scofield Prescribes
The cost of decoding our genetic makeup has plummeted in recent years. Even a decade ago, the thought of identifying all 6.4 billion base pairs of our DNA for the price of a fancy dinner for two (with a bottle of wine) would have been inconceivable.
That said, just because it’s affordable doesn’t necessarily mean it’s worth doing. And for most of us, it’s probably not.
A note to start: Services such as 23andMe provide a snapshot of your genes, analyzing 1% or so of your DNA. Whole-genome sequencing (offered by services like sequencing.com) looks at the entirety of your DNA.
In most cases, the results will be quite similar, as the more limited snapshots – known technically as genotyping – focus on those areas of our genomes where we know people can vary. And it is these variations that can be tied to disease risk.
Still, most common diseases – cardiovascular illnesses, dementias, the lion’s share of cancers – stem from complex causes, a mix of environmental and genetic factors that we have not yet fully sussed out. There’s nothing a genetic test can tell us on these fronts that’s useful.
Indeed, when it comes to preventing the health conditions that strike most of the population, we pretty much know the playbook: Exercise, don’t smoke, eat five servings of fruits and vegetables a day, minimize red meat and alcohol, and get plenty of sleep.
If you go the sequencing route, the tests will generally flag mutations that cause rare diseases. All of us carry a few mutations, but they’re nearly always recessive, meaning that unless we have two of them – which most people don’t – they won’t cause disease.
The only way these types of genes come to the surface is if you have children with someone else who is carrying the same recessive gene. In that case, there’s a 1 in 4 chance that a child will develop that disease.
Finally, researchers have linked a handful of genes to more common conditions. One specific subtype of breast cancer stems from a variant in the genes known as BRCA1 and BRCA2. While results from genome sequencing could provide a warning flag, more specific testing would be necessary to confirm the mutation, which also increases risk for ovarian and other cancers.
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Dr. Hal Scofield is a physician-scientist at the Oklahoma Medical Research Foundation, and he also serves as Associate Chief of Staff for Research at the Oklahoma City VA Medical Center. Adam Cohen is OMRF’s senior vice president and general counsel. Send your health questions to contact@omrf.org.
