The Harmony Prenatal Test is an example of an NIPT test. This test was developed by Ariosa Diagnostics and is widely used for Non Invasive Screening. The Ariosa’s Harmony test is now being undertaken by TDL Genetics at their Laboratory in London. The Harmony test is now available in more than 100 countries, and has been used to guide clinical care in over 500,000 pregnancies.
Harmony Prenatal Test is clinically validated for use in pregnant women of any age or risk category, to assess risk for trisomies 21, 18 and 13.
Harmony reduces false-positives by more than 90-fold compared to first trimester screening FTS. The performance of the Harmony test was shown to be far superior to that of traditional first trimester screening for the detection of trisomy 21 in the general pregnancy population.
Non-invasive prenatal testing (NIPT) analyses cell-free DNA circulating in the pregnant mother’s blood. It is a new option in prenatal screening for Down syndrome (trisomy 21) and other common chromosomal conditions (trisomies 18 and 13), X and Y chromosome conditions (optional). This test can be requested for any singleton or twin pregnancy, including those conceived naturally or by IVF using the patient’s own egg or a donor egg. Please note however although Fetal Sexing is now also available for twin pregnancies sex chromosome conditions cannot be analysed in twin pregnancies.
About the Ariosa Harmony™ Prenatal Test
DNA from the fetus circulates in the mother’s blood. Cellfree 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 the sex chromosome aneuploidy panel option 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. Alternatively there is also an option to look only for Turner syndrome and not the other sex chromosome conditions. 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.
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.
Clinical studies have shown that the Ariosa 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, 97% of fetuses with trisomy 18, and 94% 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 trisomic 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 this test?
The Ariosa Harmony™ Prenatal Test can be ordered by healthcare professionals for women with pregnancies of at least 10 weeks’ gestational age. This test can be requested for any singleton or twin pregnancy, including those conceived naturally or by IVF using the patient’s own egg or a donor egg. Sex chromosome (X and Y) analysis is also now available for twin pregnancies. However Harmony does not assess risk for mosaicism, partial trisomies or translocations.
The results will be ready in approximately 3-5 days.
Women still need to have their other ultrasound scans including the 12 week scan and the 18-21 week anomaly scan.
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?
Her sample and completed request form need to be sent to TDL Genetics, where the Harmony™ Prenatal Test is performed on the DNA extracted from her blood sample.
Will the mother need to have any other tests?
The Ariosa Harmony™ Prenatal Test does not provide information on other rare chromosomal abnormalities. If the ultrasound scan shows a high nuchal translucency or other major physical defects such as brain abnormalities, heart abnormalities, the risk for some rare chromosomal defects may be high. In such cases, the mother may choose to have a CVS or an amniocentesis.
The non-invasive prenatal test does not provide information on other physical defects such as spina bifida, or information on fetal growth. It is therefore advisable that the mother has all the usual ultrasound scans during her pregnancy
What is the cost of the Harmony Test?
The cost of the test is currently £450.00