A new non-invasive prenatal test for Down’s Syndrome has been launched this week by Great Ormond Street Hospital (GOSH), offering expectant mothers greater accuracy and a reduced need for invasive tests, which can lead to miscarriage.
GOSH is initially making the new laboratory test available for NHS hospitals predominantly in the north Thames region.
The new test, known as the NIPT (non-invasive prenatal test), involves a simple blood test from the mother. It is based on the relatively recent knowledge that a developing fetus’ DNA circulates in its mother’s blood, so some aspects of the baby’s genetic profile can be screened directly from the blood sample.
The NIPT offers women an accuracy rate of about 99% in detecting Down’s Syndrome in a fetus, compared to 84-90% with the conventional ‘combined test’ offered on the NHS, which involves an ultrasound scan and blood test.
In cases where the NIPT reveals a high risk of Down’s Syndrome, an invasive test (chorionic villus sampling or amniocentesis) will still be required to confirm this result. Both of these invasive tests involve putting a needle into the womb to obtain a sample of the baby’s genetic material, and have around a 0.5% chance of causing a miscarriage.
However the increased accuracy of the NIPT means it produces less ‘false positives’ than the traditional combined screening. This in turn reduces the number of women unnecessarily referred for invasive tests, thereby significantly increasing safety.
The test has been trialled as part of a larger NIHR-funded study evaluating the effectiveness of NIPT in the NHS, with support from the NIHR Biomedical Research Centre at GOSH and the UCL Institute of Child Health.
The results of the NIHR study will be available later this year, and will form the basis of a detailed report to be submitted to the UK National Screening Committee (UK NSC), the body which sets the standards for antenatal screening in the NHS.
The UK NSC will consider the results along with other data and international evidence before making a recommendation on whether NIPT should be offered as part of the current NHS Fetal Anomaly Screening Programme.
The North East Thames Regional Genetics Service Laboratory at GOSH is currently the only NHS laboratory in the UK with the capability to undertake the NIPT testing.
It will be up to each hospital that takes on the service from GOSH to decide its own exact criteria for making the test available to patients and this would be in addition, but separate, to the current NHS Fetal Anomaly Screening Programme.
Lucy Jenkins, interim director of the North East Thames Regional Genetics Service Laboratory at GOSH, said: “This test offers expectant mothers greater accuracy in detecting Down’s Syndrome and reduces the anxiety and risk associated with an invasive test.
“As with all prenatal testing, the NIPT is about providing women and their partners with knowledge and choices, and we are delighted to be the first laboratory in the country to offer this service to NHS hospitals.”
Expectant parents can access further information about NIPT by visiting www.labs.gosh.nhs.uk/NIPT or alternatively they can contact their local maternity unit to find out whether it will be providing the test to eligible patients.