In Depth

Personalized medicine: AAAS members paving the way for gene-tailored medical care

July 18, 2013 | Author: Freelance Writer Carrie Madren
AAAS members paving the way for gene-tailored medical care
AAAS Fellow Rex Chisholm, Northwestern University runs the eMERGE consortium, which uses Electronic Health Records linked biobank samples to study the genetics of disease susceptibility, therapeutic outcomes and pharmacogenomics. (Photo: Courtesy Rex Chisholm)

Over the past three years, AAAS member Michael Snyder has become a guinea pig for his own research, volunteering to regularly draw blood so his Stanford lab could track his genomes. His genetic profile, called an iPop, or integrative personal omics profile, revealed that he had a high risk of developing diabetes. “My sugar shot through the roof, and we caught it early,” says Snyder, director of the Stanford Center for Genomics and Personalized Medicine, whose project was detailed in a recent article in Pacific Standard. Armed with the new information gleaned from his iPop, he was able to change his diet as the disease progressed and prevent serious damage.

Snyder’s project is one of many unlocking clues tucked away in our DNA.            

Scientists believe that chronic diseases—such as diabetes, heart disease, cancer, and Alzheimer’s—are caused in part by genetic factors. By studying our genomes, they hope to figure out what variations lead to these diseases, as well as how doctors can treat patients more effectively. Researchers already know about a few thousand genome variations that  lead to true medical consequences—and add to that knowledge base every year.

This intense study of our genomes has paved the way for personalized medicine, the tailoring of medical treatment to the individual characteristics of a patient, according to the President’s Council on Advisors on Science and Technology.

Our bodies respond to medications slightly differently: While one treatment or medication may work well for one patient, it may not be the best solution for another. By studying a patient’s genome, doctors can know who will benefit from a prevention or therapeutic treatment, sparing expense and side effects for those who won’t. So, for example, if someone’s a poor metabolizer of a drug (because they carry a known genetic variant that reduces efficiency), doctors can alter the dosage or perhaps offer a completely different medication, explains AAAS Fellow Rex Chisholm, a professor in cell and molecular biology at the Center for Genetic Medicine and Surgery at Northwestern University.

Sequencing genomes can also yield valuable information for healthy people. Armed with specifics on their DNA, people can foresee risks and make more informed lifestyle choices.

That’s been the focus of Snyder’s lab, which is looking beyond genomes to other health markers, such as microbiomes (the microbes that flourish in our guts and even in our mouths and on our skin that help keep us healthy). Scientists are realizing the importance of these microbiomes for our overall health and studying the relationship between specific diseases and these beneficial microbes that dwell inside of us. 

Those microbiomes are just some of the billions of markers that his lab is tracking. “We don’t know which of the billions of markers we’re following right now are going to be the most informative,” Snyder says. Eventually, routine tests for regular patients will be some subset of that.

Such longitudinal studies—where patients give a regular blood sample—would help clinicians trying to catch disease early by showing changes relative to a particular individual’s baseline healthy state. “To me, that’s the nature of personalized medicine,” says Snyder.

Futuristic medicine

Among the biggest advances in personalized medicine is understanding and treating cancer, explains AAAS member Alan Shuldiner, director of the Program in Personalized and Genomic Medicine at the University of Maryland in Baltimore.

“These days, if you have cancer, there’s a good chance you’ll get your genome sequenced, and that information will lead to the possible drugs that you might take,” Snyder says. It’s also clear that cancer is a genetic disease, in terms of predisposition.

That’s why actress Angelina Jolie—whose mother died of breast cancer—used genetic testing to inform her decision to undergo a double mastectomy. The tests revealed that Jolie carried the BRCA1 gene and an 87 percent risk of breast cancer.

It’s also clear that everyone’s cancer is different. “There are some common themes, but in general they’re pretty different,” says Snyder, who says that personalized treatment will be standard of care in the not-too-distant future.

More new developments focus on mystery diseases or conditions.  In some cases, sequencing can reveal a disease that’s known and hadn’t been suspected; in other cases, there’s a completely new disease. For half of those mystery cases, researchers can at least get a short list of possibilities to narrow the field.

And as researchers gather more cases—people whose diseases or conditions share the same characteristics and whose genomes share the same mutation—databases grow.