From diagnostic yield to clinical impact: a pilot study on the implementation of prenatal exome sequencing in routine care.

PURPOSE: Exome sequencing (ES) is an efficient tool to diagnose genetic disorders postnatally. Recent studies show that it may have a considerable diagnostic yield in fetuses with structural anomalies on ultrasound. We report on the clinical impact of the implementation of prenatal ES (pES) for ongoing pregnancies in routine care. METHODS: We retrospectively analyzed the impact of pES on pregnancy outcome and pre- or perinatal management in the first 22 patients counseled for pES because of one or more structural anomalies on fetal ultrasound. RESULTS: In two cases, a diagnosis was made by chromosomal microarray analysis after ES counseling. The remaining 20 cases were divided in three groups: (1) pES to aid parental decision making (n = 12), (2) pES in the context of late pregnancy termination requests (n = 5), and (3) pES to guide pre- or perinatal management (n = 3). pES had a clinical impact in 75% (9/12), 40% (2/5), and 100% (3/3) respectively, showing an overall clinical impact of pES of 70% (14/20). CONCLUSION: We show that clinical implementation of pES is feasible and affects parental decision making or pre- and perinatal management supporting further implementation of ES in the prenatal setting.