Harmony® Prenatal Screening

Harmony is a prenatal test that analyzes cell-free DNA circulating in the mother’s blood, and detects trisomies 21, 18, and 13, as well as aneuploidies related to the fetal sex chromosomes (X and Y), through the relative quantification of the number of circulating chromosomes. This test can be performed starting at 10 weeks of gestation.

Cell-free DNA consists of DNA fragments circulating in peripheral blood that are released during cell turnover. Harmony® detects fetal cfDNA fragments released into the maternal bloodstream during pregnancy (and distinguishes them from maternal cfDNA based on different methylation patterns).

Harmony does not replace an ultrasound exam, as the latter can identify pregnancies at high risk for chromosomal and non-chromosomal abnormalities, such as congenital heart defects and Mendelian disorders.

Harmony has also been validated and is available for twin pregnancies (including all IVF cases, except for pregnancies with more than two fetuses).

A negative result on Harmony substantially reduces the risk of a pregnancy with trisomy, but a residual risk remains.

It is not possible to obtain a result in approximately 2.2% of cases due to a low concentration of fetal cfDNA (less than 4%), and in 2.6% of cases due to certain technical conditions.

Studies have demonstrated high discrimination between affected and unaffected pregnancies, as well as high discrimination for the detected trisomy. The test’s ability to detect a trisomy depends on the percentage of available fetal cfDNA and is not related to the prevalence of aneuploidy in the population.

For Trisomy 21, the DR is greater than 99% (TFP* <0.1%); for Trisomy 18, the DR is 97.4% (TFP 0.1%); for Trisomy 13, the DR is 93.8% (TFP 0.1%). The detection rate for fetal sex is >99%. The detection rate for sex chromosome-related aneuploidies varies depending on the condition (Note that performance has not yet been evaluated in cases of mosaicism or partial aneuploidies and is expected to be less robust in these situations)

*False-positive rate

One possible explanation for the lower detection rates for Trisomy 13 compared to those for Trisomy 21 is that, in pregnancies involving fetuses with Trisomy 13, there is placental-confined mosaicism with a high proportion of disomic cells (which can result in a false-negative), whereas in pregnancies with fetuses with trisomy 21, all placental cells are invariably trisomic.
Similarly, a predominantly trisomic mosaic placenta whose fetus is euploid can produce a false-positive test result. However, due to the small number of cases of trisomy 13 examined, it was not possible to obtain an exact TPV.

Harmony Prenatal Screening should be offered to all pregnant women beyond 10 weeks*.

*All singleton and twin pregnancies resulting from natural conception or IVF using the woman’s own oocytes or donor oocytes (except for pregnancies with more than two fetuses and cases of suspected or confirmed loss of one of the twins—see acceptance criteria).

Harmony® Prenatal Screening is not a diagnostic test; it significantly reduces the number of women unnecessarily exposed to invasive procedures.

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