December 9, 2010

expert reaction to new method for testing fetal genetics, to be published in Science Translational Medicine

A blood test for pregnant women that could detect virtually any genetic disorder in an unborn child without risking miscarriage has been developed by scientists.

Dr Caroline Wright, Head of Science, PHG Foundation (Public Health Genomics), said:

“”Non-invasive prenatal diagnosis would allow couples at risk of passing on an inherited condition to their child to avoid a 1% risk of miscarriage associated with invasive diagnostic tests such as amniocentesis. This pioneering study is the first to produce a genome-wide profile for the fetus from a maternal blood sample, and describes a methodology that is potentially applicable to non-invasive diagnosis of almost any genetic condition, rather than being limited to specific traits (such as the sex of the fetus) like most previous methods. However, before such a test could be offered in the clinic, a much larger study is required to determine the robustness of the technique, and numerous logistical, economic and ethical issues need to be addressed including how to deal with unexpected or incidental findings.””

Dr Christine Patch, Genetic counsellor, Chair of the British Society for Human Genetics (BSHG), said:

“”While this is a potentially interesting approach that may have benefit for some families with serious genetic disorders who are making difficult choices when having children, there are many concerns. It is too early to apply the technology widely as we are not yet able to interpret many of the results that can be generated accurately. There is much variation between individuals’ genetic make-up, some of which is important medically, but most of which is not.

“Tests like this may produce clinically useful information, but they may also be a cause of unnecessary worry and anxiety; or they may offer false reassurance in a pregnancy that has serious non-genetic abnormalities that will not be picked up by the test.

“Prenatal diagnosis with testing for specific genetic conditions for which a pregnancy is known to be at increased risk is well established for couples who wish to know whether or not their baby has inherited a particular condition; but we do not randomly test pregnancies for a long list of other conditions that may only manifest in adult life on the basis that individuals may not want to know that information when they are older.””

Alastair Kent, Director, Genetic Alliance, said:

“”The prospect of being able to detect a growing number of genetic disorders by an analysis of fetal DNA circulating in the mother’s blood is an exciting development. This offers hope to couples at risk of having a baby affected by a life limiting genetic disease. It offers the opportunity to make a diagnosis of a potential problem without the risks associated with current test such as amniocentesis or CVS. However, the number of conditions that can be detected is limited. This may change as the technology evolves, but the introduction of this as a part of ante-natal care for pregnant women will need to be carefully evaluated if the raising of false hopes is to be avoided. We must not create hype about the potential for benefit, and resist the pressure for premature introduction of non-invasive pre-natal diagnosis if women and couples are to be able to see the benefits from this development.””