Further understanding atypical Panorama non-invasive prenatal testing results via pregnancy outcomes: a retrospective study
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Authors
Reinhard, Shannon
Wiesmann, Sabrina
Issue Date
2024-05-01
Type
thesis_closed
Language
Keywords
Non-invasive prenatal testing , Panorama NIPT , atypical NIPT result , fetal aneuploidy , maternal cancer NIPT , mosaicism NIPT , Computational Biology
Genetics
Genomics
Molecular Genetics
Other Genetics and Genomics
Alternative Title
Human Genetics Theses
Abstract
Non-invasive prenatal testing (NIPT) is used to assess the risk for a pregnancy to be affected by an aneuploidy by analyzing placental cell-free DNA. Aneuploidies commonly screened for by NIPT are Trisomy 21, Trisomy 18, Trisomy 13, and sex chromosome aneuploidies. This study analyzes Natera’s unique Panorama NIPT, which utilizes SNP-based next-generation aneuploid testing. This test historically reported high-risk, low-risk, or no-call results. In 2020, Natera began reporting an additional type of result: atypical. Currently, there is limited existing literature surrounding atypical results. In order to further understand the potential cause of an atypical result, we sought to characterize pregnancy outcomes for cases that received an atypical result on the Panorama NIPT from 2020 through 2022 performed through LifeLabs Genetics. Of the 496 cases with atypical results, we were able to obtain outcome information for 235 cases. The cases were categorized into: “live birth, normal” (35.74%), normal diagnostic testing but lost to further follow-up (30.64%), diagnosed fetal abnormality (14.47%), miscarriage or intrauterine fetal demise (11.06%), unavailable outcome information (4.68%), termination (2.55%), twin-to-twin transfusion syndrome (1 case), or vanishing twin (1 case). Fetal conditions reported included: aneuploidy, mosaic aneuploidy, microdeletion or microduplication, region of homozygosity, derivative X chromosome, or other genetic syndromes. For all of the cases in which a pregnancy outcome was not determined, there was a maternal condition identified that was the likely cause of the atypical result. There were a total of 29 cases involving a maternal condition. Maternal conditions reported included: sex chromosome mosaicism, partial X chromosome deletion, derivative X chromosome, single-gene genetic syndromes, history of stem cell transplantation, use of non-self egg donor, maternal cancer and a genetic change involving chromosome 2. Given the use of NIPT to further guide prenatal care and inform a patient’s decision to undergo invasive fetal diagnostic testing or maternal genetic investigation, we hope these results can help genetic counselors and patients facing atypical results in the clinic.
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