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Safer testing for Down Syndrome?

by philippa.brice

There has been a lot of media coverage about a new and safer form of antenatal testing for Down Syndrome this week. As devoted readers of the web pages about our work and / or our wonderful Genomics and Policy news will be aware, we have a major project in this area so we really do know what we’re talking about on this one.

What is all this about safer testing then? At present, diagnosis of genetic or chromosomal disease in an unborn fetus generally requires an invasive test (think big needles) to sample fetal cells from the placenta or the amniotic fluid that surrounds the fetus; DNA from these cells is then analysed in the laboratory. Not only is the whole big needle thing not hugely appealing (and requires an expert to perform it), but it also causes miscarriage in 0.5-2% of cases. So women who know the fetus is at high risk of having a specific disease and want to know whether or not it is affected have a difficult decision to make. However, ‘non-invasive’ testing from a sample of the mother’s blood would carry no risk of miscarriage and therefore be a much better option, although I’m told that waiting for the test results is the worst part, and that wouldn’t change.

The latest media attention is because of new research from Stanford University in the US, with the publication of a promising new approach to diagnosing Down Syndrome and similar chromosomal disorders from maternal blood. But others around the world (including in the UK) are working on different techniques, and investigating alternative uses for the test, such as identifying mutations associated with rare genetic diseases.

This is a great example of how innovation could produce medical benefits. But before we all go and get pregnant and rush to our doctors asking for testing, a note of warning: it needs a lot more evaluation yet to see whether it is reliable enough to use in routine care, and to consider the potential implications of using a different type of testing. Fortunately, we have a whole team here that has been working with the right people (doctors, midwives, geneticists, patient advocates and so on) to suggest a sensible way forward. More on this with our project report in January 2009! And meanwhile, back to the grindstone…

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2 Comments

  1. Interesting developments. Are people with Down syndrome included among your “patient advocates”?

    #1 Frank Buckley

  2. Not this time, because the remit of our working group has been to look at the possible impact of alternative technologies on currently established NHS services. The Down Syndrome screening programme comes under the National Screening Committee, who are represented on the group. Patient advocates in this particular case refers to organisations such as Antenatal Results and Choices, who represent families who have a prenatal testing. At present the technology is only in experimental use for families at high risk of genetic diseases - but, of course, its potential use in screening for DS is of much wider interest. Whether screening for DS should be offered at all is a separate issue altogether, and not one under consideration in this context. But given that it IS available already, I think most people would prefer to have the option of a safer form of diagnostic testing, provided they are properly informed about it of course. How they choose to use the information it gives, if they opt for testing, would be down to them.

    #2 philippa.brice

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