From 1 September, a routine blood sample from a pregnant mother could determine very accurately whether the foetus has one of the most common chromosome abnormalities. The test is entirely without risk for the foetus, and it meets a frequent request from expectant mothers.
The blood sample can be taken after an ultra-sound examination has showed that the woman is at least 11 weeks into her pregnancy. The test can determine very accurately the likelihood for the most frequent, serious chromosome abnormalities in the foetus. The results will be given to the mother within ten weekdays.
Up to now, prenatal genetic diagnostics of chromosome abnormalities in the foetus has been by analysing the placenta or the amniotic fluid associated with a ½-1 percent risk of miscarriage.
The new NIPT test is expected to reduce the number of placenta biopsies. NIPT and the results
NIPT can detect almost all foetuses with trisomy 21 - Down syndrome (99%), trisomy 18 - Edward syndrome (96%), and trisomy 13 – Patau syndrome (91%). The test covers most (80-85%), but not all, the chromosome abnormalities that can be detected using traditional examination of the chromosomes in the placenta or amniotic fluid. An abnormal NIPT result will be followed up with an invasive test, as a false-positive result can occur, although this is extremely rare.
“The sex of the foetus can also be determined, and this may be relevant because some congenital diseases are linked to the sex of the child,” said head of the laboratory, Susanne Kjærgaard DMSc from the Chromosome Laboratory at the Department of Clinical Genetics at Rigshospitalet. Together with Peter Johansen, molecular biologist, PhD, and technologist Karina Nørgaard, she is part of the trio primarily responsible for development, validation and performance of the NIPT.
From idea to development of the NIPT
Development of the NIPT has been in close cooperation with the Centre for Foetal Medicine and Pregnancy at Rigshospitalet, which, among other things, obtained blood samples from pregnant women. The intensive project was also completed with financial support from the Capital Region of Denmark, and help from the Board of Management at Rigshospitalet and the management at the Clinical Genetic Department and at the Juliane Marie Centre.
“Prenatal genetic diagnostics has been a focus area for many years at the Department of Clinical Genetics, and this project has made it possible to implement the most modern prenatal genetic technology to benefit expecting mothers. Having implemented NIPT, we also have a platform from which to take part in the development of prenatal genetic diagnostics at high international level,” said Susanne Kjærgaard, and she concluded:
“Now we can offer a test to pregnant women; developed and validated in Denmark, and available from the public sector. Up to now, women had to go to a private clinic offering to forward blood samples to commercial firms in the US. We shouldn’t belittle this as ‘just a blood test’. The test is yet another service in the range available for pregnant women and there are also ethical aspects. Therefore, women need qualified information and advice, at the place where they are being monitored, both before and after the test”.
Other Danish hospitals are working to establish NIPT, and a working group under the Danish Health and Medicines Authority is to update the guidelines for prenatal diagnostics, including the future prospects for NIPT to be offered as a uniform test for all pregnant women in Denmark.