Jamie Stephenson has seen firsthand what modem genetic science can do for a family. When her son David was 2 years old, a pediatrician noticed developmental delays and suspected fragile syndrome, a hereditary form of mental retardation. A lab test confirmed the diagnosis, and the Stephensons spent several years learning to live with it. When David was 6, he visited a neurologist, who scribbled "fragile X" on an insurance-company claim form. The company responded promptly—by canceling coverage for the entire family of six. There is no medical treatment for fragile X, and none of David’s siblings had been diagnosed with the condition. "The company didn’t care," Stephenson says. "They just saw a positive genetic test and said, ’You’re out’. " From the dawn of the DNA era, critics have worried that genetic testing would create a "biological underclass"—a population of people whose genes brand them as poor risks for employment, insurance, even marriage. The future is arriving fast. Medical labs can now test human cells for hundreds of anomalous genes. Besides tracking rare conditions, some firms now gauge people’s susceptibility to more common scourges. By unmasking inherited mutations in p53 ( main story) and other, genes, the new tests can signal increased risk of everything from breast, colon and prostate tumors to leukemia. Many of the tests are still too costly for mass marketing, but that will change. And as the Stephensons’ story suggests, the consequences won’t all be benign. "This is bigger than race or sexual orientation," says Martha Volner, health-policy director for the Alliance of Genetic Support Groups. "Genetic discrimination is the civil-rights issue of the 21st century." No one would argue that genetic tests are worthless. Used properly, they can give people unprecedented power over their lives. Prospective parents who discover they’re silent carriers of the gene for a disease can make better-in formed decisions about whether and how to have kids. Some genetic maladies can be managed through medication and lifestyle changes once they’re identified. And while knowing that you’re at special risk for cancer may be an emotional burden, it can also alert you to the need for intensive monitoring. Jane Gorrell knows her family is prone to colon cancer. Her father developed hundreds of precancerous polyps back in the 1960s, and both she and her sister had the same experience during the ’70s. Their condition, has since been linked to a mutation in the p53 gene—and Gorrell has learned, that one of her two children inherited it. Though the child has suffered no symptoms, she gets frequent colon exams and is helping researchers test a drug that could help save lives. The catch is that no one can guarantee the privacy of genetic information. Outside of large group plans, insurance companies often scour people’s medical records before extending coverage. And though employers face some restriction, virtually any company with a benefits program can get access to workers’ health data. So can schools, adoption agencies and the military. Employees of Lawrence Berkeley Laboratory (LBL), a large research institution owned by the Department of Energy and operated by the University of California, recently discovered that the organization had for three decades been quietly testing new hires blood and urine samples for evidence of various conditions. "I can’t say the information was put to some incredibly harmful use, because we don’t know what happened," says Vicki Laden, a San Francisco lawyer who has tried unsuccessfully to sue the lab for civil fights violations. LBL recently stopped the testing. From the passage, we can infer that______.

A. people believe genetic tests are useful when they are properly used
B. prospective parents are reluctant to discover that they’re silent carriers of the gene for a disease
C. if some genetic diseases are managed through medication, lifestyle will not change
D. if a father has no risk for cancer, his son will certainly has no cancer either