Genetic testing has recently received Page 1 news attention. To know or not to know, that is your question. How do you answer? Will knowing your cells carry a gene connected to a deadly disease prompt healthy changes, or fear? Will a clean report lull people into a false sense of security, leading them to skip steps that might prevent it? How much would you want to know? Who should you tell?
Genetic Testing: To Know Or Not Know?
The FDA’s recently decided to allow 23andMe, a popular genetics firm, to tell consumers whether they carry gene mutations linked to breast and ovarian cancers. Indeed, several medical organizations and patient advocates are in favor of testing and disclosure. But they also have concerns about possible unplanned consequences.
Genetic Testing: Tests Have Serious Limitations
Most genetic testing requires a doctor’s prescription. But the new 23andMe test, which costs about $200, is the only one approved by the FDA for direct-to-consumer genetic testing so far. The mutations it tests for, which happen in genes known as BRCA 1 and 2, are most common in people of Eastern European Jewish ancestry. But the results don’t rule out the presence of more than 1,000 other mutations of those genes. And these three mutations included in the 23andMe test are not the most common BRCA1/BRCA2 mutations in the general population.
Currently, there is much uncertainty on how other mutations affect the ones that are detected for risk factors, which means the false positives and false negative rate could be high. Thus some people might take drastic action like breast removal but still be a false positive. Other people might relax and engage in riskier lifestyles, but these may be false negatives.
A false positive happens when testing says you have the mutation in your genes, but you actually don’t. A new study found that 40% of direct-to-consumer genetic tests had false positives. And a false negative is when the test says you don’t have the mutation, but you actually do.