Although the predictive ability of DTC tests in the study was moderate for all diseases, both companies assigned to an increased risk of a substantial part of the group. However, the risk of disease in this group was often substantially higher than the risk in the rest of the population studied. For AMD, the disease with the greatest predictive power, both companies took the risk in the population was about 8percent. Of all the subjects identified as an increased risk, 16percent using the 23andMe risk estimates and 19percent using estimates deCODEme would develop AMD, compared to 4percent in the rest of the population studied.Working under the supervision of Associate Professor Cecile Janssens, in collaboration with researchers from Leiden, the Netherlands, and Boston, USA, Ms Kalf examined the risk estimates provided by two large DTC companies, deCODEme (Iceland) and 23andMe (USA). Genotype data are simulated for 100,000 individuals based on genotype frequencies established and then used the formulas and risk data provided by companies to achieve the anticipated risks for eight common multifactorial diseases – AMD (age ),,,,, and type 1 and type 2 (T2D).
90percent of respondents believe that a forecast of evidence – to predict whether an individual asymptomatic had a very high probability of developing a condition – should not be allowed without face to face medical supervision, 93percent say the same for a predictive test for condition that has a penetrance (the proportion of individuals with the mutation who have clinical symptoms) and 50 to 60percent, 79percent for a test vector for single gene disorders such as homozygous sickle cell anemia, and 72percent for a predictive test condition that increases or decreases the risk of a person to develop it by 4percent than the general population.
‘Concerns about clinical geneticists’ with DTC genetic tests are mainly related to the fact that these tests usually do not have validity and clinical utility. According to the experiences of clinical geneticists, the Patients often do not know how to interpret the results they receive, and are often confused. However, almost all clinical geneticists believe they have a duty to advise the patient if I contact them after the purchase of a DTC genetic testing, ‘says Dr . Howard.
Direct-to-consumer (DTC) genetic testing to predict disease risk of inaccurate and many European geneticists believes that some of them should be banned, the annual conference of the European Society of Human Genetics are you today ‘Today (Tuesday). In the first of two studies to be presented, Rachel Kalf, Department of Epidemiology at the Erasmus University Medical Centre in Rotterdam, the Netherlands, says that his research is the first to examine the actual capacity of these predictive tests, results that are available directly to an individual, without having to go through a health care professional.
DTC companies have been criticized for giving an exaggerated and inaccurate message about the relationship between genetic information and disease risk. ‘I do not take into account genetic factors to predict the risks for consumers, while in most multifactorial diseases other modifiable risk factors such as diet, environment, exercise and smoking have a much greater impact on the risk of disease, ‘said Professor Janssens. ‘We are all aware of the ethical issues DTC genetic testing, but this study also confirms that their predictions are inaccurate. When some governments are considering the regulation of such evidence, we believe we have made a significant contribution to the debate’, he said.
One of the problems with DTC tests is that the tendency of companies to exaggerate the potential of predictive information does not help to produce a public well informed about the potential value and limitations of genetic information. This is especially true when it comes to whole genome scans, which lists many results for many different conditions, the researchers say.
‘DeCODEme predicted risk higher than 100percent for five of the eight diseases,’ said Mrs. Kalf. 100 percent, suggesting that they would definitely develop the disease. ‘
Currently, only a few European countries like France and Switzerland have legislation which states that genetic tests can only be achieved through individual medical supervision. ‘Although this model is sometimes criticized for being too paternalistic,’ says Professor Borry, ‘in the absence of a good job of pre-market control of genetic testing, could be a useful way to address some of the concerns about DTC tests . ‘
In the second study, Dr. Heidi Howard from the University of Leuven, Belgium, and his colleague Professor Pascal Borry reported the results of a survey on a representative sample of clinical geneticists from 28 countries throughout Europe on their experience and attitudes of DTC genetic testing. Howard says, ‘and the results were conclusive – 69percent of respondents believe that prenatal testing should generally be prohibited by law, and 63percent wanted to ban any analysis of the genome by DTC companies. ‘
Currently, DTC genetic tests reach the market without having undergone any form of regulation. ‘Better regulation is necessary for the introduction of these tests,’ says Professor Borry. As with drugs, a procedure should be developed for genetic testing. ‘
‘So people in the group at risk can be four times the risk of disease, but are much more likely not to develop the disease at all. For T2D, where companies have calculated the average risk about 25percent, 32percent of those assigned to the group at greatest risk of developing type 2 diabetes is actually from 22percent in the rest of the population studied. This difference in disease risk is too small to be significant, ‘said Professor Janssens.