Comparison of QF-PCR and FISH for Aneuploidy Detection in Prenatal Diagnosis

Introduction: Among all chromosomes (46) in the human genome, particular significance has been given to chromosomes 13, 18, 21, X and Y. This is primarily because of aneuploidy in these chromosomes that result in viable pregnancies with congenital defects. As a result, standardised methods like Rapid Aneuploidy Test (RAT) for detection is the need of the hour in addition to Non-Invasive Prenatal Testing (NIPT) and Chromosomal Microarray (CMA). Aim: To compare and analyse the diagnostic utility of Fluorescent In-Situ Hybridization (FISH) and Quantitative fluorescent Polymerase Chain Reaction (QF-PCR) in aneuploidy of detection. Materials and Methods: In the present observational study, 120 pregnant women suspected of having fetal aneuploidies were subjected to amniocentesis and Chorionic Villus Samplling (CVS). Following DNA extraction, FISH and QF-PCR were carried out using pre-designed chromosomal markers and specific FISH probes for trisomy of 13, 18 and 21. Results: Of 120. 5 prenatal samples showed Trisomy (T) 13. 18 and 21 chromosomes, amounting to a frequency of 4.2% (5/120). These results were concordant by both tests i.e FISH and QFPCR trisomy 18 and 21 detected. Four amniotic fluid samples, two each respectively (4/108; 3.7%), and one Chorionic Villus Sampling (CVS) (1/12: 8.3%) were tested positive for trisomy of chromosome 13. Conclusion: From the present study, it can be concluded that QF-PCR is a better technique for detection of aneuploidies. However, both these techniques, together called RAT of Invasive Prenatal Screening (IPS) should be performed for errorless results before termination of pregnancy (TOP).