The Womens Health Clinic is delighted to offer their patients the Harmony test – Non Invasive Prenatal Testing (NIPT).This is a simple blood test which analyses cell-free fetal DNA circulating in the mother’s blood, and can be done after 10 weeks gestation.
It is a screening test for Down Syndrome (Trisomy 21), Edward’s Syndrome (Trisomy 18), Patau’s Syndrome (Trisomy 13) as well as X and Y chromosome conditions, microdeletions, and the sex of the fetus if requested.
It is necessary to have had a scan prior to the blood test to have accurate dates and to know if this is a single or multiple pregnancy.
NIPT has a high accuracy for assessing fetal trisomy risk. It identifies more than 99% of Trisomy 21, 98% of Trisomy 18 and 80% with Trisomy 13.
The sex of the fetus, if requested, is determined with >99% accuracy.
About the Harmony test
DNA from the fetus circulates in the mother’s blood. Cell-free DNA (cfDNA) results from the natural breakdown of fetal cells (presumed to be mostly placental) and clears from the maternal system within hours of giving birth.
During a pregnancy, cfDNA can be tested to give the most accurate screening approach in estimating the risk of a fetus having a common chromosome condition sometimes called a trisomy. This occurs when there are three copies of a particular chromosome instead of the expected two. The test looks to detect the following trisomies:
Trisomy 21 is the most common trisomy at the time of birth. Also called Down syndrome, it is associated with moderate to severe intellectual disabilities and may also lead to digestive disease, congenital heart defects and other malformations.
Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome) are associated with a high rate of miscarriage. These babies are born with severe brain abnormalities and often have congenital heart defects as well as other birth defects. Most affected individuals die before or soon after birth, and very few survive beyond the first year of life.
Sex chromosome conditions. The sex chromosomes (X and Y) determine whether we are male or female. X and Y chromosome conditions occur when there is a missing, extra, or incomplete copy of one of the sex chromosomes. The Harmony with X, Y test can assess risk for XXX, XYY, XXYY, XXY (Klinefelter syndrome), and a missing X chromosome in a girl (Turner syndrome). There is significant variability in the severity of these conditions, but most individuals have mild, if any, physical or behavioural features. If the mother is interested in having this optional testing, she should talk with her healthcare provider to determine if it is right for her. This option is not available for twin pregnancies.
Risk
The testing is non-invasive: it involves taking a blood sample from the mother. The pregnancy is not put at risk of miscarriage, or from other adverse outcomes that are associated with invasive testing procedures such as amniocentesis.
Accuracy
Clinical studies have shown that the Harmony Prenatal Test has exceptional accuracy for assessing fetal trisomy risk.
A ‘high risk’ result is indicative of a high risk for a trisomy. The test identifies in singleton pregnancies more than 99% of fetuses with trisomy 21, 98% of fetuses with trisomy 18, and 80% of fetuses with trisomy 13, and 96% of fetuses with Turner Syndrome. X and Y analysis provides >99% accuracy for fetal sex. Accuracy for detecting other sex chromosome anomalies varies by condition.
After the test, the number of women required to have a CVS or an amniocentesis is less than 1%.
It is important to note that if the test results show there is a high risk that the fetus has trisomy 21, 18, 13 or sex chromosome conditions, it does not mean that the fetus definitely has one of these conditions, although it is highly likely. For this reason, in the event of a ‘high risk’ (or positive) result, follow-up testing by an invasive procedure is recommended.
In the same way if the test results show that there is a ‘low risk’ that the fetus has trisomy 21, 18, 13 or sex chromosome conditions, it is unlikely that the fetus has one of these conditions. However, there is a very small risk that not all trisomy fetuses will be detected. All results should be interpreted by a clinician in the context of clinical and familial data. Patients should continue with their usual scan appointments following testing.
Who can have the test?
The Harmony test can be ordered by healthcare professionals for women with pregnancies of at least 10 weeks’ gestational age. The Harmony test can now be ordered for all IVF singleton pregnancies, including those with egg donors. Samples from pregnant women with twins naturally conceived, or those conceived using the patient’s own egg, are also accepted. This test does not assess risk for mosaicism, partial trisomies or translocations.
The results will be ready in approximately two weeks. On the basis of the NIPT result a patient can decide whether or not she wants to have an invasive procedure (for example, CVS or amniocentesis).
Repeat samples
There needs to be enough fetal DNA in the maternal blood to be able to provide a result. If there is insufficient fetal DNA in the sample (occurring in 3% of cases), another blood sample from the mother may be required. This will be processed in the laboratory at no extra charge.
What is the process?
Once the mother has taken an independent personal decision that she wants to have the non-invasive prenatal test performed, she will be asked to sign a consent form and her blood sample can be taken from a vein in her arm.
Who carries out the analysis of the test?
The sample and completed request form need to be sent to TDL Genetics, after which they will be referred to Ariosa Diagnostics Inc, USA. Ariosa performs the Harmony™ Prenatal Test on the DNA extracted from her blood sample.
Will the mother need to have any other tests?
The non-invasive prenatal test does not provide information on other physical defects such spina bifida, or information on fetal growth. It is therefore advisable that the mother has all the usual ultrasound scans during her pregnancy.
Transfer of the mother’s information outside the European Union
For the purposes of carrying out the Harmony test, the mother’s personal information will be transferred outside of the European Union, to the USA. Please be aware that the laws applicable to her personal data in the USA are different from those operating in the UK, where TDL Genetics is established.
