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Ariosa’s Harmony test is now being undertaken by TDL Genetics. This validated transfer of technology ensures same performance and accuracies but with a reduced turnaround time of 3-5 days. Worldwide interest and adoption in Ariosa Diagnostics’ Harmony™ test has been growing steadily. The Harmony test is now available in more than 100 countries, and has been used to guide clinical care in over 500,000 pregnancies.
The recent rapid adoption of the Harmony Test worldwide can be attributed to:
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
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:
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.
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 can have their 12-week scan for a detailed examination of the fetal anatomy, including measurement of nuchal translucency, nasal bone and other important factors. In this visit, patients can discuss the DNA and ultrasound results with their obstetricians.
On the basis of the NIPT result and the ultrasound findings, a patient can decide whether or not she wants to have an invasive procedure (for example, CVS or amniocentesis).
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.
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.
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.
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.
|Test||Code||Sample Type||Turnaround Time|
|Non-Invasive Prenatal Testing – common aneuploidy screening from maternal blood||NIPT
||Two 10ml tubes of maternal blood –special tubes provided by the laboratory