Experts discuss pioneering non-invasive test to determine the blood type of unborn babies

Sep 25 2007

Experts from across the world will meet to discuss the implementation of a pioneering non-invasive test to determine the blood type of unborn babies at an event hosted by the University of Warwick.

The Special Advances in Fetal and Neonatal Evaluation (SAFE) Network of Excellence is holding a two-day workshop at the De Montfort Hotel in Kenilworth on the 26th and 27th of September. The symposium will discuss issues associated with implementation of new Non-Invasive Prenatal Diagnostic (NIPD) tests based on minute traces of fetal DNA in the mother’s blood. Large scale uses for various types of population screening are being considered, both inside and outside the UK.

Currently, this new type of test can be used to identify fetal blood group in pregnancies where the woman is rhesus negative. This is especially important if the fetus itself is rhesus positive, in which case the woman may become sensitised and develop antibodies against her own child. Such sensitisation can result in haemolytic disease of the newborn, with antibodies in the mother’s blood attacking her baby’s blood cells leading to jaundice and anaemia or, in extreme cases, death. Currently, over 110,000 women a year in the UK are given a blood product (anti-D) to prevent such sensitisation during their pregnancy. A large number of these women do not need this form of prophylaxis because their baby will not have a rhesus positive blood group. The new test could bring benefits to these women, and to the NHS in terms of saved expenditure on anti-D. At the same time, the new tests are expensive. The meeting will debate the technical performance, costs and benefits of this new form of testing and its potential for widespread implementation in different countries.

For already sensitised women (500-600 pregnancies/year in the UK) NIPD tests could replace the use of amniocentesis (an invasive test used to identify the blood group of the fetus) which is associated with 1% risk of miscarriage. NIPD test implementation could therefore bring very important clinical benefits to these women.

NIPD tests are being developed in laboratories throughout the world following the observation that circulatory cell-free fetal DNA is present in maternal plasma and serum. Techniques for extracting and amplifying this DNA have already begun to impact on clinical practice as a reliable and efficient alternative to invasive testing to identify fetal blood group and, when clinically necessary, to determine the sex of a fetus. The SAFE Network (funded by the European Commission) is dedicated to developing non-invasive tests for use in the diagnosis of other genetic conditions such as cystic fibrosis, beta-thalassaemia and Down’s syndrome.

The symposium is being led by the University of Warwick Medical School. Warwick’s Professor Ala Szczepura said: "We look forward to insightful discussions and hope to come to conclusions about test implementation at the population level in the UK and other countries."

Speakers will include experts from Germany, the Netherlands, France, UK, India and the USA. Key international findings from industry on test development, from laboratory scientists on test performance, from economists on the cost-effectiveness of new testing programmes, and from policy makers/regulators on implementation issues will be presented and discussed. In particular, the workshop will open the debate on patients’ views of the perceived risks and benefits of such new tests.