Everyone's genes spell out a risk for some disease, and a coming anti-discrimination law is about to give genetic testing a boost.
But discrimination is just one hurdle. The bigger quandary: Doctors don't yet know how many of the genetic tests being pushed for dozens of conditions are truly useful -- and how many are misleading at best.
"Some of these tests are complete rubbish," warns Dr. Howard McLeod, a personalized medicine specialist at the University of North Carolina. "The big challenge for a consumer is figuring out which data is real or not without having to go to medical school."
President Bush is expected soon to sign into law federal protection against genetic discrimination, a bill barring employers and insurers from using test results against patients.
First to benefit will be people who put off learning if they inherited genes responsible for diseases that run in their families -- breast cancer, colon cancer, Huntington's, early-age Alzheimer's -- for fear of losing insurance coverage or a job.
No one knows how many people that encompasses. The National Institutes of Health estimates 30 percent of potential volunteers for gene studies cite discrimination fears in backing out. At the same time, states have adopted a patchwork of protections, and steadily growing use of two of the best-proven tests -- for the BRCA1 and BRCA2 gene mutations linked to breast and ovarian cancer -- suggests that lingering concern hasn't been a huge deterrent for people with strong family histories of disease.
But until now, most genetic testing has been for conditions linked to single genes gone wrong, typically rare ones.
That's changing.
Most diseases -- including diabetes and the No. 1 killer, heart disease -- are caused by complex interactions of multiple genes and environmental factors, such as diet, exercise and smoking. With scientists rapidly discovering gene variants for these more common conditions, genetic testing in turn is poised to boom.
Specialists advise anyone considering a gene test to:
-- Consult a doctor or one of the nation's 3,000 genetic counselors, to weigh pros and cons.
-- Ask what the results will mean for siblings or children. How big is their risk, and do they want to know?
-- Ask how accurate the test is, and if knowing you've got a risky gene allows you to take steps for better health or just worry.
Not finding one particular gene for, say, breast cancer or diabetes doesn't mean you're off the hook for standard checkups; other genes could still sicken.
Dr. David Altshuler of Harvard Medical School offers a scary example: He had a patient with a rare type of diabetes caused by a single gene mutation. One of her sons didn't inherit it -- but he was at risk for more common Type 2 diabetes simply because he was overweight.
Yet, "he said, 'Now I'm through with diabetes,' and had some ice cream," Altshuler recalls.
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