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


About this study

Panorama® is a commercially available Laboratory Developed Test (LDT) certified under the Clinical Laboratory Improvement Amendments (CLIA). This test has not been cleared or approved by the U.S. Food and Drug Administration (FDA). Panorama analyzes SNPs to distinguish maternal from fetal (placental) DNA, targeting 13,932 SNPs covering chromosomes 21, 18, 13, X and Y, to determine chromosomal abnormalities and fetal sex. Panorama is used in twin pregnancies to screen for a variety of abnormalities, including trisomies 21, 18 and 13, monosomy X zygosity and fetal sex for each twin.

The primary objectives of this study are to use the Panorama® testing to:
1) Develop a new algorithm and methodology that will distinguish between the non-viable or demised twin and the living twin in dizygotic twins with a single living twin..
2) Assess the accuracy of the new algorithm to determine which of the signals in the Panorama samples correspond to the living twin versus the non-viable or demised twin. .

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria:

  • Female age 18 or older at the time of signing informed consent.
  • Ultrasound confirmation of singleton pregnancy.
  • GA ≥ 9 weeks at the time of first sample collection.
  • Willing and able to provide written informed consent.
  • Willing and able to comply with study procedures, including blood sample and neonatal buccal swab.
  • Cohort 1: Ultrasound confirmation of VT Pregnancies:
    • Ultrasound confirmation of VT;
    • Spontaneous fetal demise of one twin or empty sac.
  • Cohort 2: High Risk for VT Pregnancies:
    • Panorama yielding “high risk for twin/VT/triploidy” result;
    • Ultrasound confirmation of single gestation;
    • No evidence of triploidy.

Exclusion Criteria:

  • Known monozygotic twin pregnancy.
  • Multiple gestation.
  • VT pregnancy resulting from iatrogenic fetal demise.
  • GA < 9 weeks.
  • Evidence of triploidy other than Panorama test results.
  • Any confounding complication or condition that, in the opinion of the investigators, precludes participation in the study; this may include a cancer diagnosis, organ transplant, pregnancy utilizing an egg donor, or other findings that may interfere with interpretation of Panorama results.

Eligibility last updated 10/19/21. Questions regarding updates should be directed to the study team contact.

Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status Contact

Rochester, Minn.

Mayo Clinic principal investigator

Myra Wick, M.D., Ph.D.

Open for enrollment

Contact information:

Maureen Lemens C.C.R.C.

(507) 293-1487

More information


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