Blood test for Down's syndrome detection hailed
New test on pregnant mothers returns fewer 'false positive' results
Friday 07 June 2013
A new non-invasive blood test can reliably detect whether or not an unborn baby has Down's syndrome during the first trimester of pregnancy, researchers said today.
The test, which analyses a baby's DNA present in its mother's blood, could be an improvement on current screening methods, according to the study.
Down's syndrome, and other chromosomal disorders characterised by an additional chromosome, is currently tested for between the 11th and 13th weeks of a pregnancy, using an ultrasound screen and a hormonal analysis of the pregnant woman's blood. The only definitive test involves chorionic villus sampling and amniocentesis but that carries a risk of miscarriage.
A study carried out at the Harris Birthright Centre at King's College London is the first to look at the feasibility of screening for the chromosomal disorders - known as trisomies - using foetal cell free DNA (cfDNA) from a pregnant woman's blood.
The tests, carried out at the 10-week stage on 1,005 pregnancies, were found to be more sensitive at detecting Down's syndrome and returned fewer "false positive" results than the combined tests usually carried out between the 11th and 13th weeks. The cfDNA test returned false positive rates of 0.1 per cent compared to 3.4 per cent for the combined tests.
The authors of the study, published in the Ultrasound in Obstetrics & Gynecology journal, said: "This study has shown that the main advantage of cfDNA testing, compared with the combined test, is the substantial reduction in false positive rate. Another major advantage of cfDNA testing is the reporting of results as very high or very low risk, which makes it easier for parents to decide in favour of or against invasive testing."
They also found that if cfDNA testing is carried out after a combined test at 11 to 13 weeks, 98 per cent cases of Down's syndrome could be detected. Invasive testing was then needed for confirmation in less than 0.5 per cent of cases.
The authors added: "Screening for trisomy 21 by cfDNA testing contingent on the results of an expanded combined test would retain the advantages of the current method of screening, but with a simultaneous major increase in detection rate and decrease in the rate of invasive testing."
The study involved mothers-to-be at King's College Hospital, London.
Life & Style blogs
Video shows how to turn your phone into a 3D hologram
Gill Pharaoh: Healthy former nurse, 75, passes away at assisted dying clinic after deciding old age is 'awful'
Free porn websites could be shut down within months, says David Cameron
The difference between a psychopath and a sociopath
National Orgasm Day: Six reasons (plus one bogus one) why they're good for us
- 1 Video shows how to turn your phone into a 3D hologram
- 2 Artist Jamie McCartney: How The Great Wall of Vagina is a stand against 'body fascism'
- 3 Katie Hopkins reveals fear she will die during brain surgery to cure epilepsy
- 4 'Gene drive': Scientists sound alarm over supercharged GM organisms which could spread in the wild and cause environmental disasters
- 5 Dutch King Willem-Alexander declares the end of the welfare state
£18000 - £26000 per annum: Recruitment Genius: This is an opportunity for an I...
£17000 per annum: Recruitment Genius: They are a leading company in the field ...
£30000 - £35000 per annum: Recruitment Genius: This is an exciting opportunity...
£26041 - £34876 per annum: Recruitment Genius: There has never been a more exc...