False Genetic Testing Results Condemned by Doctors
The inaccuracy of a genetic test that gave false positives to patients has resulted in doctors calling for a crackdown on genetic testing.
If a woman’s BCRA gene is faulty, her risk of breast and ovarian cancer is much higher than average. People with a family history of these cancers are often tested to identify their BCRA gene variants to determine their risk level. If the risk level is high then doctors can recommend the appropriate preventative surgery, a mastectomy or an ovariectomy, to reduce the risk of cancer developing.
As the price of home genetic testing kits decreases and their popularity increases, more people are able to test for their risk level independently. However, a recent study has concluded that the testing method used for the BCRA genes are not accurate enough to be used for genetic testing and ‘should not be used to guide health decisions without validation.’ The testing method is commonly used by commercial genetic testing companies.
The study showed that for people with rare BCRA variants the test for a faulty variant gave a false positive 84% of the time. The sensitivity, which determines how likely the test was at predicting the presence of the high risk BCRA variant in someone that has it, was only 34.6%.
The study found that for common variants the test was accurate at identifying the risk level, but the likelihood of a true positive result decreased with decreasing allele frequency. Therefore, if the patient has a rare variant of the gene the accuracy of any genetic test will be substantially lower.
These results have generated concern in the medical community, who say that the inaccuracy or misinterpretation of the genetic testing results could lead to women having surgery, and risking surgical complications, when it is unnecessary. There is also concern about how poor the test was at predicting patients who did have the faulty variants. These patients would not be given the monitoring required to ensure an early diagnosis, or the opportunity to have preventative surgery.
It is clear that serious consideration needs to be had about releasing genetic tests results to patients if their risk level cannot be determined.