The Harmony test, like other forms of Non-Invasive Prenatal Testing (NIPT) can detect a number of different chromosomal or genetic conditions. One of the conditions that it can test for is Down syndrome. Read on to learn how NIPT can detect these kinds of conditions and how reliable the Harmony test results will be. It’s essential for you to understand what the test can detect and how you should interpret the results before you decide to have the Harmony test or any other form of NIPT.
What is NIPT?
NIPT is a special kind of blood test that you can have during pregnancy
in order to screen for certain conditions that could be affecting your baby. All we have to do is take a sample of your blood, in the same way as any other blood test. We can find fragments of placental DNA in your blood, which is identical to your baby’s DNA. By analysing this, we can tell if your baby is likely to be affected by certain genetic or chromosomal conditions.
The Harmony test is one of the most widely known forms of NIPT in the UK
, but you can also have the Panorama or SAFE tests at the Birth Company. All of these tests can detect the most common chromosomal abnormalities, including Down syndrome. However, it’s important to understand that screening tests can only tell you if your baby is at higher probability of a particular condition. NIPT cannot be used to diagnose any condition for certain, so you may need to have another test to confirm the results.
How Does NIPT Detect Down Syndrome?
We usually have 23 pairs of chromosomes. Most cases of Down syndrome happens when there is an extra copy of one of these chromosomes, known as chromosome 21. The Harmony test and other forms of NIPT can detect this by analysing which chromosomes the fragments of DNA in your bloodstream belong to. If there are more fragments than expected from a particular chromosome, this indicates that the baby is likely to be carrying an extra copy. If the extra fragments were from chromosome 21 then this means that there is a high probability that your baby has Down syndrome.
What Else Can NIPT Detect?
Down syndrome is one of the most common and widely known chromosomal conditions, affecting about 1 in 1000 babies. However, there are other conditions that can happen when there are extra copies of other chromosomes. NIPT can also screen for these kinds of conditions. Although different types of NIPT can screen for slightly different problems, the most common issues that they will look for are:
- Edward’s syndrome, caused by an extra copy of chromosome 18
- Patau’s syndrome, which happens when there is an extra copy of chromosome 13
- Sex chromosome conditions, such as Turner syndrome, which happens when a girl has only one X chromosome instead of the usual two
You should discuss the different screening tests that are included in NIPT with your doctor so that you can choose the right type of test for you. All types of NIPT, including the Harmony test, can check for Down syndrome. However, there are some extra tests that you might want to be included if you are at risk of certain other conditions.
Understanding Your NIPT Results
Non-Invasive Prenatal Testing is a type of screening test. What this means is that it can tell you if your baby is likely to be affected by a specific condition, but it cannot diagnose this condition for certain. When you get your results back, you will see that you are given a risk or probability for each of the conditions that was being screened. For example, for the Down syndrome result you will be told that your baby is either at low risk or high risk of the condition.
The results you get from NIPT are very reliable, but no screening test can get it right 100% of the time. The Harmony test can detect more than 99% of babies with Down syndrome. This means that if we tested 100 babies with Down syndrome, we would detect the condition in at least 99 of them.
However, it is important to remember that in a small number of cases:
- A baby who is at higher risk could turn out not to have the condition (this is called a false positive, and it happens in less than 0.1% of Harmony tests for Down syndrome)
- A baby who is considered to be at lower risk might actually be affected by the condition
If you have any questions about your results then you should discuss them with your midwife or meet with one of the NIPT experts at the Birth Company. The results that we get from these kinds of tests are very accurate, but they aren’t the only evidence that we have to assess the risk of Down syndrome and other chromosomal abnormalities. Your sonographer can also check for signs of Down syndrome during your nuchal scan
and factors such as your age can also be used to determine how likely your child is to be affected. If the Harmony test or NIPT results show that there is a high risk of Down syndrome, the result can also be confirmed by amniocentesis or Chorionic Villus Sampling (CVS). These are both invasive tests that pose some risks to your baby, but they are the only way to be absolutely sure of the result before your baby is born.
The results of your Harmony test or other NIPT can play an important role in assessing the risk of Down syndrome and similar conditions. Most babies who are affected by Down syndrome can be detected by these tests, but it’s important to remember that NIPT is a screening test rather than a diagnostic one.
Now that you know more about how NIPT can detect Down syndrome and other abnormalities, are you going to have this screening test?