Unraveling Your DNA's Secrets
Do-it-yourself genetic tests promise to reveal your risk of coming down with a disease. But do they really deliver?
NeuroMark says the purpose of the test is "educational," and it is not attempting to assist doctors in diagnosing depression. "That would be a reach," says CEO Kim Bechthold, who notes the firm no longer sells the depression test because of "enormous demand." It plans to reintroduce the test in mid-2007.
Fear of disease is a powerful motivation to seek out genetic testing, and that's certainly the case with blindness. Age-related macular degeneration and glaucoma are two leading causes in people over age 55. Macular degeneration causes deterioration in the retina; with glaucoma, excess pressure within the eye damages the optic nerve. A test for macular degeneration and glaucoma, sold for $99.95 by CyGene Laboratories of Coral Springs, Fla., looked at three variants in the myocilin gene. But those are just three of the 80 to 100 myocilin changes associated with glaucoma. Our tester, a 37-year-old woman with abnormally high pressure on glaucoma tests, got this news: "You do not have an increased risk for developing Primary Open Angle Glaucoma over the general population." That may or may not be true. "It's just too small a slice," says Janey Wiggs, an ophthalmologist at Harvard Medical School who is leading a national study of the genetics of glaucoma. "You could easily miss a mutation that could be related to very severe glaucoma." So far, Wiggs says, genetic testing is useful only in patients with early onset of glaucoma and a family history of the disease, something that our tester doesn't have. The best way to screen for disease, Wiggs says: Go to the eye doctor. Martin Munzer, CEO of CyGene, says that "we could do a comprehensive vision panel, but nobody would be able to afford it." His company's test, he says, is not definitive, but "it's like chicken soupit won't hurt you." He agrees that regular eye exams are the best screening tool.
When considering do-it-yourself genetic testing, customers need to be certain the tests are performed properly. "People should be aware that there is no regulation of the quality of the tests that are being sold over the Internet," says Kathy Hudson, director of the Genetics and Public Policy Center at Johns Hopkins University. "They may not be certified labs, and even if they are, the regulations for laboratory quality really are general and have minimal standards. They don't assess whether a laboratory is able to accurately do genetic tests."
The FDA, which approves drugs and medical devices, deems genetic tests "services," devised by the labs that perform them. And the Centers for Medicare and Medicaid Services, which regulates medical laboratories under the Clinical Laboratory Improvement Amendments, or CLIA, has balked at creating special oversight for genetic tests. At a minimum, people ordering genetic tests should ask if the laboratory is certified under CLIA. "I would also look for a lab that's participating in the College of American Pathologists or ACMG proficiency testing," says ACMG's Watson. Four of the testing companies we used, DNA Direct, HealthCheckUSA, Kimball Genetics, and NeuroMark, use CLIA-certified labs. CyGene plans to apply for CLIA certification this month, Munzer says.