Bbc Inside Science

Dr Adam Rutherford uncovers the worrying number of false positive results that the DNA sequencing technologies used by 'direct to consumer' genetic test kits are producing. Many of these tests offer analysis on your ancestry, but some also offer to check you out for the likelihood of you being at risk of some genetic diseases like cystic fibrosis or certain types of breast cancer. The tests look for variants in your genome, little changes in your DNA that alter the risk of developing a number of genetic diseases. The trouble is the rarer the variant, the more likely it is to be disease-causing. But the rarer the variant, the more likely the simple genetic tests are to get it wrong. And with more and more people sending off their raw genetic data to third-party websites for analysis and annotation, the risk of a false positive result increases to up to 80%. It's a small number of people affected, but a serious one if you're told out of the blue that you are at extreme risk of a serious disease. The advice is