CGS-authored
Out of curiosity, he checked back three months later and found that the company, called deCODE, had changed its assessment: His risk was now below average.
DeCODE had recalculated its algorithm, based on new data. Davies, who is himself a geneticist by training, wasn't too surprised by this about-face: "The information that these companies can give you can change and evolve over time," he says.
That isn't the only way today's genetic tests offer slippery conclusions. According to a US government study, results often vary widely among genetic-testing companies, largely because each has its own way of choosing and analyzing data.
When the project to map human DNA was finally completed in 2003, many predicted a revolution. Drugs could be chosen to match individual patients with maximum therapeutic effect and minimum side effects, the advent of...