Harmony Blood Test for Downs Syndrome Screening
The Harmony Prenatal Test Why the Harmony test?
For the last ten years doctors have been using the results of the Nuchal Translucency Scan to advise pregnant women and their partners on their risk of having a baby with Downs syndrome, or other abnormalities. The Nuchal Translucency Scan looks at the skin fold on the back of the baby’s neck at about 12 weeks. This has been further refined by looking at the nose bone of the baby with an additional blood test to identify two pregnancy hormones. This is the combined test and has achieved a predictive value of about 92%. Women with a high risk have an option to proceed to chorion villous sampling (CVS) or amniocentesis. These are invasive tests that carry a miscarriage risk of about 1:100. This is changing. The Harmony blood test has become available.
What is the Harmony test?
It has been discovered that a blood sample taken from the mother at any time from 10 weeks of pregnancy can be analysed for cell free fetal DNA, which is essentially a marker in the mother’s blood of the DNA of the baby. The result of the simple blood test (Harmony) is predictive to more than 99%, which will hugely reduce the need for invasive testing by CVS or amniocentesis. This is great news for couples because it eliminates the risk of miscarriage of the pregnancy. It is important that an ultrasound scan is performed just before the blood test to confirm the pregnancy, and to check that is the mother is not carrying twins or more. The Harmony can now be used if the pregnancy is conceived with donated egg. The result of the Harmony is predictive to more than 99%. This will hugely reduce the need for invasive testing by amniocentesis or chorionic villous sampling. This is great news for the couple because it eliminates the risk of miscarriage of the pregnancy.
Who needs the Harmony Test?
Anyone who is anxious about her baby having a chromosomal abnormality such as Downs, Edwards or Patau’s syndrome can have it. It is predicted that in 10 years it will become available for all on the NHS. Women who may need it are those that are older (particularly over 40 years), have already had a chromosomally abnormal pregnancy or who are at particular risk of miscarriage should they have an amniocentesis or chorionic villous sample.
How is the test done?
- The mother has to read and sign a consent form and sign a form for data release.
- An ultrasound scan is usually done first to check the baby is alive and date the pregnancy and check for twins. This can be done from 10 weeks gestation and up to the end of the pregnancy.
- This is a simple blood test from the vein in the woman’s arm like any other blood test. There is no risk from having the test.
- Two tubes need to be fully filled.
- The tubes are immediately packaged and couriered to the Laboratory in LOndon.
How long does it take to get a result?
The result is usually available within 3-5 days. There is a one in thirty chance that no DNA is obtained. This is not a positive or negative test: it is an unsuccessful test. An offer of a repeat test is made free of charge. This is usually successful.
How is the result expressed?
The result is expressed as a probability. It is a screening test and not a diagnostic test. A good test result gives a risk of a chromosomal problem of less than 1:10000. A bad result gives a risk of 1:2. A risk of 1:2 requires an amniocentesis or chorionic villous sampling depending on the clinical situation. The couple are counselled about this. Rarely the chromosomes of the baby may be normal. Rarely there is a test result that requires further investigation.
How much does it cost?
The test is currently £475 including the dating ultrasound scan. On some occasions we can use a previous scan report, in which case the cost of the Harmony blood test would be £375. If you need a scan at a later stage in the pregnancy the cost will depend on how far pregnant you are.
Are there problems this test will not detect?
Yes. Structural abnormalities such as Spina Bifida, heart defects and a poorly growing baby will only be seen on scans and often not until later scans.
The Harmony Blood Test does not replace the Combined Test as you still need the 12 week scan to assess the nuchal translucency (NT) and check for structural abnormalities.
You can have the Harmony blood test and scan from 10 weeks. You can also have your Combined Test blood test done at the same time if you are having both tests. However some people decide to have the Combined Test first and then proceed to the Harmony blood test if the Combined Test result is not as reassuring as they would like.
We recommend having the Harmony Test at 10 weeks +/- a scan – this depends on whether you can provide a written report of a previous scan you have had done. If not we will need to do a dating scan for you as we need to know exactly how many weeks pregnant you are, check the baby is alive and check whether you are expecting twins.
Those who are very high risk may decide to proceed to an invasive procedure such as a CVS (Chorion Villus Sample) or if the risk is borderline you may decide then to have the Harmony Test as this carries no risk to the fetus.
It is important to know that The Harmony Test does not exclude all rare syndromes such as Noonans Syndrome.
If you have had a Combined Test where the nuchal translucency has shown to be increased, in particular over 3.5mm and your overall risk for Down’s syndrome is increased , you may still wish to consider an invasive procedure. This is because an increased NT (nuchal translucency – the fluid on the back of the baby’s neck) can be a marker for other rare syndromes besides Down’s syndrome as well as fetal abnormalities such as cardiac/heart defects. An increased nuchal translucency can also be normal.
It is very important to get correct counselling so that you know which test is both appropriate and best for you.
The Harmony Test can also reveal the sex of the baby. We therefore will need to know whether this is something you wish to find out. If not, we can issue a report without the sex of the baby on it.
This new test has been developed by Ariosa Diagnostics www.ariosadx.com and is quality controlled by Ariosa Diagnostics and a laboratory in London that we use.