Funded by grants from the National Institutes of Health, Dr. Green and his colleagues have conducted surveys among users of the tests. Among 1,057 consumers who responded to a survey six months after taking either a 23andMe test or one from another company, 28% had discussed the results with a doctor, 11% had undergone additional tests or procedures and 3% had discussed results with a genetic counselor, according to the researchers' preliminary findings presented at a recent meeting of the American Society for Human Genetics.

Whether such doctor visits and additional tests reflect smart or wasteful use of medical resources or lead to improved health for patients isn't known, but researchers are looking at such questions, said Dr. Green, who doesn't have financial ties to any makers of personal genetic tests.

Dr. Green said he isn't aware of any cases of harm from the tests.

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