The tests that are listed below are commercially available; however, they are considered laboratory-developed tests (LDTs) and are not FDA-approved as of 2024. Cell-free fetal DNA (cffDNA) tests, commonly referred to as cfDNA or NIPT are not considered diagnostic and a “low-risk” test result does not suggest an unaffected pregnancy while a “high-risk” test result still requires an invasive confirmatory test.
MaterniT21® PLUS test
MaterniT21® PLUS test, developed and validated by Sequenom Center for Molecular Medicine (CMM), analyzes circulating cell-free DNA extracted from a maternal blood sample. This test is presently available from Labcorp's Integrated Genetics division and utilizes the MPS technology to identify increased numbers of chromosomes. In the test, circulating cell-free DNA is purified from maternal plasma and the DNA is analyzed for chromosomal material and converted into a genomic DNA library for the determination of chromosome 21, 18, 13, and Y representation based on massively parallel DNA sequencing.
The MaterniT21® PLUS test has reported performance characteristics for Downs syndrome (T21) of 99.1% (sensitivity) and 99.9% (specificity; for Edwards syndrome (T18) of 99.9% (sensitivity) and 99.6% (specificity); for Patau syndrome (T13) of 91.7% (sensitivity) and 99.7 (specificity). Test results are reported as "negative" or "positive" for trisomies.
Verifi® Prenatal Test
This test is offered by Verinata Health, a subsidiary of Illumina Inc. The test also utilizes MPS technology. Verifi® Prenatal Test uses a normalized chromosome value (NCV) calculation for each chromosome tested. This NCV calculation removes variation within and between sequencing to optimize the test precision. Test results are reported as “no aneuploidy detected”, “aneuploidy suspected" for borderline cases, and “aneuploidy detected” for the respective chromosome tested. The test claims to have a >99.9% sensitivity and 99.8% specificity for the detection of Down syndrome. For Edwards and Patau syndromes, the reported sensitivity and specificity are 97.4% and 99.6%; 87.5% and >99.9%, respectively.
Harmony Prenatal Test®
This test, developed by Ariosa Diagnostics*, targets fetal DNA with its proprietary digital analysis of selected regions (DANSR). It analyzes cfDNA in maternal blood with microarray quantitation. As with other cfDNA tests, the Harmony® prenatal test is best performed any time after the tenth week of pregnancy. Using the DANSR methodology, the Harmony® Prenatal Test analyzes sequencing results of selected, targeted genomic regions on chromosomes 21, 18, and 13. The test results will yield an assessment of the risk for trisomy 21, 18, and 13. Using a specific algorithm, the test results are reported out as an individualized risk for each trisomy. The test claims to have a 99.1% sensitivity and >99.9% specificity for Down syndrome. Edward and Patau syndromes are reported to have sensitivity and specificity of 97% and >99.9; 94% and >99.9%, respectively.
*Ariosa Diagnostics was acquired by Roche in 2015.
