The Future of Medicine: Diagnosis by DNA
Doctors had done everything to treat six-year-old Nicholas Volker’s inflammatory bowel disease. They’d tried drugs and done numerous surgeries, eventually removing his colon. Yet nothing helped. Desperate, his doctor wrote to researchers at the Medical College of Wisconsin, asking them to take the unusual step of sequencing Nicholas’ genome. They did — at a cost of $75,000 — and discovered a mutation on his X chromosome, which was causing an uncontrolled immune response that affected his intestinal tract. They gave him an umbilical-cord-blood transplant, essentially providing him with a new immune system. A year later, though still vulnerable, Nicholas eats normally, plays sports and is back at school.
Scientists have known for decades that genome sequencing — decoding some or all of the three billion pairs of DNA we each carry — could revolutionize medicine. It has long been used for research, but Nicholas’ case took it further: It proved the procedure could also be used for diagnosis and treatment.
“Right now, medicine is one-sizefits- all,” says Kerry Bowman, a bioethicist at the University of Toronto. “If we knew our genomes, the efficiency of treatment would jump.” It could also potentially show patients their genetic disposition to health problems, so they could take pre-emptive action or change
their lifestyles accordingly, says Cheryl Shuman, director of genetic counselling at the Hospital for Sick Children in Toronto.
But that doesn’t mean doctors will have all the answers, cautions Bowman. Genes aren’t isolated triggers; they react to one another and to outside variables, and scientists believe it’s those complex interactions that cause many diseases. Still, some global health companies are so excited about the technology’s potential — and the market — that they’re in a race to make gene sequencing cheap enough for all doctors to use. “The magic price point seems to be around $1,000,” says Steve Scherer, director of the Centre for Applied Genomics at the Hospital for Sick Children. The cost has plummeted from $300 million in 2003 to roughly $5,000 today, and it’s expected to hit the $1,000 mark within the next five years.
“Genomic sequencing’s revolutionizing our basic understanding of disease, and things are moving quickly,” says Marco Marra, director of the B.C. Cancer Agency’s Michael Smith Genome Sciences Centre. “We could wake up next year with whole-genome sequencing in much, much wider use. It’s not as distant as people think.”