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Clinician‐reported chorionicity and zygosity assignment using single‐nucleotide polymorphism‐based cell‐free DNA: Lessons learned from 55,344 twin pregnancies
Author(s) -
Wojas Anna,
Martin Kimberly A.,
Koyen Malashevich Allyson,
Hashimoto Katelyn,
Parmar Sheetal,
White Roseann,
Demko Zachary,
Billings Paul,
Jelsema Russ,
Rebarber Andrei
Publication year - 2022
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.6218
Subject(s) - zygosity , medicine , obstetrics , snp , twin pregnancy , single nucleotide polymorphism , gestational age , monochorionic twins , pregnancy , gynecology , gestation , genotype , genetics , biology , gene
Abstract Objective Prenatal chorionicity assessment relies on ultrasound, which can be confounded by many factors. Noninvasive assessment of zygosity is possible using single nucleotide polymorphism (SNP)‐based cell‐free DNA testing. Our objective was to determine the relationship between provider‐reported chorionicity and SNP‐cfDNA assignment of twin zygosity. Methods All twin pregnancy blood samples received by a reference laboratory between September 27, 2017 and September 8, 2021 were included. Chorionicity assignment was requested on the requisition, recorded as; monochorionic (MC), dichorionic, or “don't know”. SNP‐cfDNA zygosity results, monozygotic (MZ) or dizygotic (DZ), were correlated with chorionicity assignment. Results 59,471 twin samples (median gestational age = 12.0 weeks at draw) were received and analyzed; 55,344 (93.1%) received zygosity assignment. SNP‐cfDNA reported 16,673 (30.1%) MZ and 38,671 (69.9%) as DZ. Provider‐reported chorionicity was compared to the zygosity assignment for each case. Of 6283 provider‐reported MC twins, 318 (5.1%) were reported as DZ using SNP‐cfDNA. Conclusion(s) One in 20 suspected MC twin pregnancies were reported as DZ using SNP‐cfDNA. Approximately 30% of 55,344 twin pregnancies were found to be MZ, including cases where chorionicity was unknown. SNP‐cfDNA zygosity assessment is a useful adjunct assessment for twin pregnancies, particularly those reported as MC or without determined chorionicity.