1005 Prenatal diagnosis of genetic disorders: trends in screening and invasive testing

Abstract

Prenatal genetic screening and diagnosis continues to evolve, with more options to screen for single gene disorders (SGD) and aneuploidy. Our objective was to evaluate changes in screening and diagnostic testing in those undergoing prenatal diagnosis. We identified all patients undergoing invasive testing at our center from 2015-2019. Screening for single gene disorders was categorized as targeted vs. expanded. Genetic disorders were categorized as chromosomal, copy number variant (CNV), or single gene disorder (SGD). Temporal trends were evaluated using Chi-square for trend for categorical and Spearman’s rho for continuous variables. Continuous data are expressed as Median [IQ Range]. A p-value <.05 was considered statistically significant. 1761 pregnancies were included. Screening for SGD was expanded in 74.6% and targeted in 25.4%, and 57.5% had screening with cell-free fetal DNA (cfDNA). CVS was performed in 839 patients (47.6%) and amniocentesis in 922 (52.4%). Genetic conditions were diagnosed in 158 pregnancies (9.0%), including 88 (55.7%) with abnormal karyotype, 34 (21.5%) with CNV, and 36 (22.8%) with SGD. 98 (5.6%) underwent abortion for genetic conditions. Table 1 describes trends in screening, testing, and diagnosis. There were significant changes in screening over time, with increasing rates of expanded carrier screening and cfDNA. Fetal testing for SGD disorders did increase during the study period to greater than one-fifth of invasive tests, though this trend did not reach statistical significance (p=.06). There were no differences in types of fetal genetic conditions diagnosed or timing of abortion. In pregnancies in which carrier screening led to fetal diagnostic testing, the proportion of SGD that could only be identified with expanded screening increased significantly (Table 2). We observed significant changes in screening for SGD and aneuploidy over time. Expanded carrier screening has led to a higher proportion of carriers of SGD who could only be identified with expanded screening, and this may lead to higher rates of invasive testing for SGD.View Large Image Figure ViewerDownload Hi-res image Download (PPT)