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Poster Session 1

Category: Genetics

Poster Session 1

(153) Utility of expanded carrier screening for identifying risk of inherited genetic disease in anomalous fetuses

Wednesday, February 11, 2026

10:30 AM - 12:00 PM

Submitting Author and Presenting Author(s)

Carmen M.A Santoli, MD (she/her/hers)

Maternal Fetal Medicine / Medical Genetics and Genomics Fellow
University of California, San Francisco
University of California, San Francisco, California, United States

Coauthor(s)

Billie R. Lianoglou, MS (she/her/hers)

Genetic Counselor
University of California, San Francisco
San Francisco, California, United States
NS

Nuriye Sahin-Hodoglugil, MD, PhD

Program Manager
University of California, San Francisco
San Francisco, California, United States
KT

Katie Tick, MPH

University of California, San Francisco
San Francisco, California, United States
Rozlyn C.T Boutin, MD, PhD (she/her/hers)

Postdoctoral Fellow & Medical Genetics and Genomics Resident Doctor
University of California, San Francisco
San Francisco, California, United States
Kate Swanson, MD (she/her/hers)

Assistant Professor
University of California, San Francisco
San Francisco, California, United States
PD

Patrick Devine, MD, PhD

University of California, San Francisco
San Francisco, California, United States
JV

Jessica Van Ziffle, PhD

University of California, San Francisco
San Francisco, California, United States
Mary E. Norton, MD (she/her/hers)

Professor of Obstetrics, Gynecology & Reproductive Sciences
University of California, San Francisco
San Francisco, California, United States
Teresa N. Sparks, MD, MS (she/her/hers)

Associate Professor, Maternal-Fetal Medicine and Clinical Genetics
University of California, San Francisco
San Francisco, California, United States

Objective:
Expanded carrier screening (ECS) panels are designed to identify reproductive risk for inherited autosomal recessive (AR), and in some cases, X-linked (XL) conditions. However, many fetal genetic diseases are sporadic or inherited through other mechanisms. We aimed to determine the proportion of all fetal genetic diseases, as well as the proportion of inherited AR and XL conditions, detectable by ECS.

Study Design:
Retrospective cohort study of pregnancies that underwent genomic sequencing for ultrasound anomalies (2017-2024) and had at least one pathogenic or likely pathogenic variant indicating a fetal genetic disease. We calculated the proportion of pregnancies with inherited fetal AR and XL genetic diseases and evaluated the actual carrier screening pursued. Further, we calculated the theoretical diagnostic yield of commercially available ECS panels for predicting fetuses at risk for the inherited conditions observed in our cohort.

Results:
Of 153 pregnancies with a fetal genetic diagnosis identified by genomic sequencing, 65 had inherited diseases and 88 occurred sporadically. Twenty-nine (19%) had inherited AR or XL conditions (25 and 4, respectively). Twenty-one of these (72%) underwent carrier screening and only one at-risk couple was identified for a genetic condition unrelated to the fetal anomaly. The theoretical diagnostic yield of ECS for identifying the 29 AR and XL inherited conditions in our cohort ranged from 0-52% due to variant classification and number of genes evaluated (Fig 1). At most, 10% of the 153 fetuses with a monogenic disease in our cohort could have been identified through ECS (Fig 2).

Conclusion:
Only 19% of our cohort had an inherited AR or XL genetic disease, and at most half of these could theoretically be detected based on current ECS panels. There are risks and benefits to ECS, and a negative result does not eliminate risk of inherited or sporadic fetal genetic disease. Clinical counseling should emphasize the limitations of ECS and include the option for fetal genomic sequencing to address the breadth of potential etiologies.