Imagine visiting your doctor and being advised to get a particular genetic test. Instead, you open your laptop and pull up a list of all 3 billion chemical “letters” that make up your full genome (the entire set of genes that comprise your DNA).
Or, perhaps you have your genetic blueprint, or “genome sequence,” encoded in a chip on your health insurance card. Swipe it through a reader when you visit your clinic, and then you, your doctor and your DNA can formulate a health plan that best suits your genetic makeup.
These scenarios quickly are becoming not only possible, but probable. “Personalized medicine” is speeding toward the day when everyone carries their genes in their jeans pocket.
The implications of personalized medicine are many, most especially for people with genetic neuromuscular diseases. But be sure to keep in mind that, as is true with many things in life, with the good also comes the bad.
Tailor-made for your DNA
In 1990, a multinational team of researchers for the Human Genome Project, using the DNA of several individuals, began mapping the human genome. Ten years later, a rough draft was presented at the White House, and in 2003 the entire reference sequence was completed.
The cost of sequencing the first individual human genome, in 2007, was approximately $400 million. In September 2010, the National Human Genome Research Institute (NHGRI) announced 10 new grants totaling more than $18 million to drive development of a "third generation" of DNA sequencing technologies able to quickly and inexpensively determine an individual's genome sequence. NHGRI-funded scientists and other researchers are working toward the “$1,000 genome,” and some companies aim to drop the cost to double digits by 2012.
Researchers now are using tools and techniques derived from the Human Genome Project, into combination with recent science discoveries and technological advances, to move personalized medicine to the next level.
Through genome analysis, scientists have identified genes that carry mutations responsible for human diseases and have begun working on new strategies for diagnosing, treating and preventing them.
In some cases, they can assess an individual’s health risks and the chances of passing down a condition to future offspring. Soon it may be possible to customize vaccines, early-stage interventions, therapies and cures, based on each individual’s biological factors.
In neuromuscular disease research, personalized medicine is already in development. One example, in Duchenne muscular dystrophy (DMD), is the promising strategy exon skipping, which coaxes cells to “skip over” sections (exons) of the dystrophin gene.
Exon skipping can be “personalized” to work for the approximately 13 percent of people with DMD who might be helped by skipping exon 51; the approximately 12 percent who could benefit by skipping exon 45; and the 11 percent for whom skipping exon 44 would be beneficial. In the future, additional exons may be “personally” addressed by this technology.
Personalized medicine faces a whole host of challenges before it can go mainstream. Researchers are still studying how to make hard and fast connections between a gene and a disease. They also need to identify reliable “biomarkers” — biological indicators of, among other things, disease onset and progression, and the effectiveness of treatments.
Computing power is a rate-limiter as well. The immense amount of data generated from a single genome scan must be analyzed before conclusions can be reached.
Physicians must learn how to incorporate genomics into their day-to-day medical practice, including learning how to interpret and relay the information genetic scans provide.
Personalized medicine, personal decisions
Learning about the possibilities your medical future may — or may not — hold comes with consequences.
Especially at this early stage, scientists and clinicians may be able to identify flaws or variants in your DNA that are known risk factors for disease or other health issues. But because other factors — in your genetic makeup or your environment, or both — come into play, having a specific stretch of DNA associated with a disease is in no way a guarantee you’ll actually develop that disease.
Given the uncertainty involved, it’s worth asking: If given the choice, how much disease-risk feedback would you want to receive? What if the information points to high risk for a condition that has no treatment or cure? How will you let it affect your well-being, your life and your medical decision-making? Will you be able to live in the present, without anticipating what your genes tell you might come in the future?
Those who decide to have their DNA tested may be confused by what a particular genetic mutation means, and genetic counselors may be necessary to prepare individuals for what they may learn and how it can or should be used.
The Genetic Information Nondiscrimination Act (GINA) prohibits employers and health insurance companies from discriminating on the basis of genetic tests. Still, many fear privacy issues if they submit their DNA for sequencing.
It’s your body, your genes, your disease and your health. Personalized medicine continues to get more personal and, for those willing to face the drawbacks, promises many benefits for people with and without genetic diseases.
To learn more about genome analysis, read the story about research scientist James Lupski, who has Charcot-Marie-Tooth disease (CMT), in James Lupski's Research into His Disease Paved Way Toward Personalized Medicine in this issue of Quest.