Evaluating the Effectiveness of Quantitative Fluorescent Polymerase Chain Reaction as a Substitute or Complement to Conventional Karyotyping for Prenatal Diagnosis

Background: This study endeavors to assess the efficacy of quantitative fluorescent polymerase chain reaction (QF-PCR) as an alternative adjunctive modality to conventional karyotyping for prenatal diagnostic purposes. Methods: In this cohort study, 464 pregnant women deemed at high risk for chromosomal aneuploidies within gestational age 12–24 weeks, spanning from January 2020 to May 2023 were enrolled. Analysis was done on 347 women who underwent both QF-PCR and karyotype. Results: Within this cohort, concordant QF-PCR and karyotype results were achieved in 332 (95.67%) samples with 21 women showing trisomy 21 and two trisomy 18 in the fetus with results being 100% concordant with karyotype and QF-PCR. Notably, there were no false-negative or false-positive QF-PCR results. However, eleven cases presented discordant results, revealing various genetic abnormalities, such as deletions, translocations, inversions, and mosaicism. The overall frequency of chromosomal abnormalities was 8.82% (41/464). The mean age of the pregnant women was 28.7 ± 5.54 years, with 10.7% (50/464) of women having aged > 35 years. The median gestation age for amniocentesis and CVS procedures was 16 weeks (IQR 15.6–20) and 13 weeks (IQR 12.7–13.5), respectively. Conclusion: The study concluded that although QF-PCR may serve as a stand-alone diagnostic tool in some cases with appropriate pretest counseling, simultaneous karyotyping, or chromosomal microarray should be considered in pregnancies with normal QF-PCR results and abnormal USG findings such as increased nuchal translucency or structural malformations or a family history of a chromosomal disorder. Despite being a rapid and highly sensitive test, QF-PCR does not fully substitute conventional karyotype analysis.