Twenty-Two Years of Prenatal Testing for Suspected Monogenic Disorders: A Retrospective Single-Center Experience in Western Romania.

BACKGROUND/

objectivesPrenatal testing strategies for suspected monogenic disorders have changed considerably over the past decades, alongside evolving referral indications and increasing availability of genomic technologies. Longitudinal, practice-based data describing these changes within routine clinical care remain limited, particularly in Central and Eastern Europe. We describe changes in referral indications, testing strategies, and molecular findings over 22 years in a single-center retrospective descriptive case series from Western Romania.

methodsWe conducted a retrospective analysis of 52 pregnancies investigated for suspected monogenic disorders between 2004 and 2026. Forty pregnancies were evaluated through a diagnostic pathway, while a separate group of 12 pregnancies underwent cell-free DNA (cfDNA)-based monogenic screening; these were analyzed as distinct clinical pathways. For the diagnostic pathway, clinical indications, testing strategies, and molecular findings were analyzed across three retrospectively defined study periods (2004-2013, 2014-2019, and 2020-2026).

resultsWithin the diagnostic pathway, referral patterns shifted from predominantly family-history-based testing (55.6% of cases in 2004-2013) toward indications arising from positive parental carrier screening and fetal ultrasound abnormalities in later study periods. Testing strategies expanded from predominantly targeted single-gene testing and multiplex ligation-dependent probe amplification (MLPA) to include gene panels and whole-exome sequencing (WES). Among 34 pregnancies with fetal molecular evaluation, 7 (20.6%) had a confirmed disease-causing finding, 9 (26.5%) had carrier-only outcomes, 15 (44.1%) were classified as unaffected, and 3 (8.8%) had non-classic molecular findings. Incidental or additional molecular findings beyond the primary testing indication were identified in 6 of 34 pregnancies with fetal molecular evaluation (17.6%) and required case-specific interpretation and genetic counseling. The 12 cfDNA-based monogenic screening pregnancies constituted a separate, non-diagnostic screening pathway and were analyzed independently from the diagnostic pathway.

conclusionsOver 22 years, referral indications for suspected monogenic disorders broadened alongside an expansion of prenatal testing strategies from predominantly targeted familial testing to a wider range of genomic approaches. These findings describe temporal changes within a single-center clinical practice and should not be interpreted as evidence that changes in testing strategy improved diagnostic performance or pregnancy outcomes. Invasive diagnostic testing and cfDNA-based monogenic screening represent distinct clinical pathways and should be interpreted separately.