79: How much is too much when it comes to cell free DNA GENOME testing?

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The purpose of this study was to evaluate outcomes for patients with positive cell free DNA GENOME studies in order to better understand how helpful these results are in affecting patient management. This is a retrospective descriptive study reviewing all patients at our institution who underwent MaterniT GENOME testing. GENOME testing was made available to high risk patients presenting for genetic counseling starting November 2015 to May 2017. Patients undergoing cell free DNA testing could choose to undergo either MaterniT21 PLUS Core with sex chromosome aneuploidies (C) (testing for trisomy 13, 18, 21 and sex aneuploidies) or MaterniT GENOME (G) (genome wide fetal aneuploidy testing). For this study we analyzed those choosing to undergo MaterniT GENOME. From November 2015 to May 2017, 495 patients (42%) chose Core testing, and 671 (58%) chose GENOME. Of the 671 patients who chose GENOME, 29 patients (4.3%) had abnormal results (Image 1). Eighteen of these (2.7%) had positive results that would have been detected from the more basic testing (C), while 11 (1.6%) had abnormalities found specifically due to the GENOME testing(G). The table lists the abnormalities detected on GENOME testing and the outcomes of these pregnancies (Table 1). Four patients had spontaneous miscarriages; six of the seven remaining patients had amniocentesis, 5 of which had normal results. Four of the seven patients delivered healthy infants, while the other 3 had either a preterm delivery or growth restriction. Overall, 3 out of the 671 patients (0.004%) had GENOME results that were relevant to antenatal management. At this time GENOME testing can lead to false positive results and adds little to Core (C) cell free DNA testing. GENOME results rarely affect management and a true assessment of risks, benefits, and cost needs to be determined.View Large Image Figure ViewerDownload Hi-res image Download (PPT)