May 31, 2011
Flawed And Inaccurate Results Found In Genetic Tests
An investigation into direct-to-consumer (DTC) genetic tests found flawed and inaccurate results, with each one giving different results, and in some cases arriving at medical predictions that were no more accurate than flipping a coin, a Dutch study has found.
The findings of the study will increase calls for tighter regulations around personalized genetics tests which can cost more than $800. Critics decry the tests as a waste of money that could mislead people about their future health, The Guardian is reporting.Researchers used a program to simulate genetic information for 100,000 typical people. The formulas from two of the largest genetic testing companies, deCODEme and 23andMe, were then used to predict the risk of eight medical conditions, including heart attack, prostate cancer, celiac disease, an eye disease known as age-related macular degeneration and diabetes.
"When we looked at individual risk of disease, we saw enormous differences between the two companies," said Cecile Janssens, an epidemiologist who led the research. "A major problem with these tests is that they don't take other factors into account, such as your age, diet, exercise and whether you smoke, which in most cases have a greater impact on disease risk.
"For complex diseases, if you ignore these non-genetic factors, you are looking at only a small part of the picture and missing the main story," she continued.
"deCODEme predicted risks higher than 100% for five out of the eight diseases", explains Rachel Kalf, from the department of epidemiology at Erasmus University Medical Center. "This in itself should be enough to raise considerable concern about the accuracy of these predictions "“ a risk can never be higher than 100%.
A result greater than itself raises concerns over the accuracy of the tests, the researchers will tell the European Human Genetics Conference in Amsterdam .
But Kari Stefánsson, the chief executive of deCODEme, said the Dutch team had misinterpreted the computer models their findings were based. "We never report a lifetime risk over 90%. This is not how we use these models."
"We are aware that most people will be at low risk for most diseases "“ this is what we expect, and is not an indication of inaccuracy. "23andMe takes extensive measures to provide both accuracy and to highlight the context for relevance at all steps in the process of analyzing and presenting data. In addition, research undertaken by 23andMe seeks to expand relevant findings." Brian Naughton, founding scientist at 23andMe explained to the Guardian.
"Lastly, 23andMe cautions that conclusions regarding 23andMe's accuracy and relevance should not be based on review of deCode or others."
At the moment, DTC genetic tests are available with no form of regulation. "Better regulation is needed at the level of market introduction of these tests," says Professor Pascal Borry from the University of Leuven, Belgium. "As in the case of drugs, a procedure should be developed for genetic tests."
Currently only a France and Switzerland, have legislation that states that genetic tests can only be accessed via individual medical supervision. "Although this model is sometimes criticized for being too paternalistic", says Professor Borry.
"In the absence of a good working pre-market control of genetic tests, it could be a useful way of responding to some of the concerns over DTC testing."
Genetic testing services available outside the regular healthcare system can also lead to unnecessary visits to healthcare providers and hence an increased burden on healthcare resources, the researchers say.
On the Net:
- Erasmus University Medical Center
- European Society of Human Genetics
- European Human Genetics Conference
- University of Leuven