Quantitative Scientist Myriad Genetics Oakland, California, United States
Introduction: Outcomes in pregnancies with rare autosomal trisomies (RATs)—defined as trisomies in any autosomal chromosome other than 13, 18, or 21—are not well characterized, with most studies having small sample sizes. We aimed to characterize outcomes in individuals who screened positive for RATs by prenatal cell-free DNA (pcfDNA) testing. Methods: Patients who received Prequel (Myriad Genetics, Inc.), a whole genome sequencing-based pcfDNA screen, between 2019 and 2022 and screened positive for at least 1 RAT were included. Patients under age 18 years, positive for ≥5 RATs, or with a multi-gestation pregnancy were excluded. Eligible patients were linked to Komodo’s Healthcare Map insurance claims data using Datavant tokenization. Pregnancy outcomes were estimated using diagnosis codes, procedure codes, and pharmacy fills. Results: 626 pregnancies were eligible for analysis. The median maternal age was 33 years (IQR: 9) and the median gestational age at testing was 12 weeks (IQR: 2). Trisomies 7 (Nf249; 40%), 16 (Nf46; 7%), and 20 (Nf84; 13%) were the most commonly observed RATs. 210 pregnancies (33.5%) had a diagnosis code for ‘suspected fetal congenital anomaly’. Of 460 pregnancies with observed pregnancy outcomes, 240 (52.2%) resulted in live birth and 70 (15.2%) resulted in miscarriage; those resulting in stillbirth or elective termination were too few (N < 11) to report. Of the 240 live births, 48 (20.0%) were preterm. Conclusion/Implications: Using a novel approach of linking pcfDNA results to claims data, we observed outcomes in pregnancies that screened positive for RATs among one of the largest cohorts analyzed to date.
