Genetic Counseling

School of Health and Human Sciences

InformaSeq®: An Exploration of High Fetal Fraction
Capstone Project Committee: Michelle Burch, MS, CGC, Lauren Doyle, MGC, CGC, Chevonne Eversley, PhD, Edward Williams, MBA, MS, CGC
Objective: To describe the experience of LabCorp since the implementation of reporting fetal fraction (FF) by determining which maternal and fetal characteristics, if any, are associated with high fetal fraction as well as to explore any possible difference in FF between screening results. Methods: This is a retrospective analysis of pre- and post-testing data collected from January 2016 through January 2017. Various maternal and fetal characteristics were compared for samples where FF was above and below the 95th percentile, and above and below the 99th percentile. Results: A total of 110,521 samples were used for analysis. All analyzed factors reached significance using the 95th and 99th percentiles (p≤0.001) except for fetal number at the 99th percentile (p=0.028). In samples above both percentiles, the frequency of aneuploidy detected (ANYS) was higher than expected (2.2% and 3.1%) yet inconsistently observed for each individual aneuploidy. There was no significant difference between the average FF between possible screen result categories (p=0.388). Conclusions: Maternal Hispanic ethnicity, abnormal ultrasound findings (ABUS) indication, third trimester gestations, and total ANYS screen results are associated with high levels of FF.
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