Verification of Risk Assignment for Whole Chromosome Using SNP-based NIPT in Vanishing Twin Pregnancies

Primary outcomes

• Develop a new algorithm and methodology that will measure fetal fraction and distinguish between the DT (demised/non-viable twin) and living twin (LT) in dizygotic twins (DZ) with a single LT. [2 years]: A new algorithm will be written to analyze the serial research blood samples to return a fetal fraction of each twin, and identify which twin is the DT verses the LT. The fetal fraction measurement will be a percentage, and it will be measurable, or not measurable for each sample.
• The accuracy of the new algorithm to determine which of the signals in the Panorama samples correspond to the LT versus the DT. [2 Years]: Each complete participant in the study will have multiple maternal blood samples collected, and a child buccal swab. This outcome will use genetic analysis to reflect for each participant if the algorithm correctly or incorrectly identified the LT versus the DT. Accuracy, defined as the number of VT pairs correctly identified as the LT and DT, divided by the total number of VT pairs, will be calculated.

Secondary outcomes

• The accuracy of the updated algorithm for the assignment of risk for trisomy 21/18/13 for the LT in DZ twins with a single LT. [3 Years]: If a sufficient number of trisomy 21/18/13 cases are observed among any of the cases, assess the accuracy of the updated algorithm to correctly determine whether the LT or DT is aneuploidy. Point estimates and 95% confidence intervals for the specificity for the aneuploidy algorithm.

Sex: Female, ages: 18 Years to any

Inclusion Criteria:

* Women with either ultrasound-documented dizygotic (DZ) twin pregnancy or those whose Panorama Test™ results suggest increased risk for vanishing twin

Exclusion Criteria:

* Monozygotic twin pregnancy
* Non twin pregnancy
* Maternal history of bone marrow or organ transplantation

• Lorraine Dugoff, MD, Principal investigator, University of Pennsylvania