What Your Genome Can Tell You
Though still in its infancy, DNA sequencing has the potential to explain everything. Here’s what doctors know now and a preview of what’s to come.
A person’s genome can tell them a lot about health risks, but it can also send false alarms. Some mutations, like the one associated with Huntington’s disease, indicate high risk. Others, like the so-called Alzheimer’s gene, may show increased risk, but hardly guarantee future dementia.
Genomic risk and reward is defined in percentages, which can lead to some difficult decisions. If a woman’s genome indicates she has a 50 percent chance of developing breast cancer, does it make sense to get a prophylactic mastectomy? What if her risk is 20 percent?
These are the conundrums that make headlines, but genomic data can tell us about a lot more than disease risk. For example, it can personalize medications and doses for individual patients.
“If someone is going on an antidepressant or an antipsychotic drug, based on how they are predicted to metabolize that drug, there are some drugs that would be more effective than others,” says Glenn Braunstein, chief medical officer at Pathway Genomics in La Jolla’s UTC area.
For Braunstein and others, the key to making genomic information useful is making it actionable. Ideally, genomic data would outline specific changes that help people overcome their genetic risks.
This is already happening in small ways. Aetna piloted a program that uses genetic testing to help employees with metabolic syndrome and other conditions manage their disease. Researchers at Harvard have shown that genomic information can help people make better decisions about their health.
“If you know you’re at risk for a condition, and there’s something you can do to ward it off, you will take that action,” says Braunstein.
We know quite a bit right now about cancer, heart disease, diabetes, rare diseases, and how people metabolize pharmaceuticals. So having your DNA sequenced is already worthwhile. And, obviously, the more people we sequence, the more we learn. This is particularly true of specific diseases. Right now there are many “variants of unknown significance,” or mutations that tend to show up in certain diseases but have yet to be conclusively identified as driving the disease or simply as innocent bystanders.
“The future is doing genomes when people are born and updating that information constantly as we figure out what all the data means,” says Braunstein. “If you could predict celiac disease and not expose young children to gluten, you could avoid a lot of discomfort.”
There are still issues to work out: data security and a dearth of genetic counselors are at the top of the list. However, having a personal genetic database could pay huge dividends.
“If we have genomic information on individuals from the start, we’ll have an incredible amount of information about medications, metabolism of medications, cardiovascular predisposition, diabetes, and obesity,” says Braunstein. “These can all help guide lifestyle and other decisions.”