Mail order gene testing blasted
Tuesday May 31st, 2011
Experts blasted private companies that offer "mail order" genetic testing today - calling for many of their activities to be banned.
Scientists revealed details of their analysis of testing offered by two of the companies at a conference today - accusing them of giving consumers "inaccurate" predictions which exaggerate their risk.
The findings were revealed at the conference of the European Society of Human Genetics in Amsterdam, the Netherlands, and were backed by a survey of clinical geneticists showing that most would support bans.
Professor Cecile Janssens, of Erasmus University Medical Centre, Rotterdam, and researcher Rachel Kalf reported an analysis of formulas used by two large "direct to consumer" companies.
They applied these to some 100,000 people, identifying the proportion who would be told they were at increased risk of developing different genetic diseases.
One example involved type 2 diabetes. The researchers concluded that just 32 per cent of those who would be told they were at increased risk would actually develop the disease. This compared with 22 per cent of those would be told they were not at risk.
Professor Janssens said the difference in risk was "too small to be of relevance."
They found that for five diseases one company would predict risks "higher than 100 per cent".
Professor Janssens said the key problem with the tests was that they took no account of lifestyle factors, which often had a bigger impact than genes on disease risk.
She said: “We are all aware of the ethical problems surrounding direct to consumer genetic testing, but this study also confirms that their predictions are inaccurate."
Dr Heidi Howard, of the University of Leuven, Belgium, reports the findings of a survey of clinical geneticists from 28 European countries.
Some 63 per cent wanted bans on whole genome scans and 69 per cent want pre-natal gender tests to be banned.
* Scientists at the conference urged doctors to move forward with using embryo-based diagnosis to help prevent genetic diseases arising from mutant mitochondrial DNA.
Mitochondrial DNA is an ancient form of DNA within cells that is specifically passed on by the mother. Mitochondrial gene defects can cause a huge range of life-threatening or disabling illnesses and affect as many as one in every 5,000 babies.
Now scientists say studies suggest that combining genetic diagnosis with test-tube baby treatment - IVF - could help prevent the birth of babies with these diseases.
A study involving the Netherlands, Australia and the UK looked at tests involving some 327 families and 159 disease-causing mutations of mitochondrial DNA (mtDNA).
Reporting to the conference of the European Society of Human Genetics, the scientists say that developing the technique is especially important as it is not possible to conduct pre-natal diagnosis when the baby is in the womb.
According to their findings, a level of mutant DNA of 18 per cent or less within the embryo will indicate that a future baby would have a less than five per cent chance of having a genetic disease.
Researcher Dr Debby Hellebrekers, of Maastricht University Medical Centre, Maastricht, said: "Our research enables us to give genetic counselling to women at risk with respect to their reproductive choices and to provide them, for the first time, with the opportunity to give birth to a healthy baby.
"The prevalence of mtDNA disorders is 1 in 5,000, which means that the families of about 146,000 patients in Europe can now have the option of having a healthy child. This is a choice that they do not currently have."
She added: "Currently, there are no effective treatments for mtDNA disorders.
"Although we cannot guarantee that a mutant mtDNA level of 18% or lower will result in the birth of an unaffected child, we think that the chances of having a healthy child are high enough to make using PGD in this instance morally acceptable."
Tags: Australia | Childbirth and Pregnancy | Europe | Genetics | UK News
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