Segmental Duplication – Quantitative Fluorescent- Polymerase Chain Reaction: An approach for the diagnosis of Down syndrome in India

Objectives: Early detection of high risk pregnancies of DS is the main target of offering prenatal diagnosis. Segmental Duplication Quantitative Fluorescent PCR (SD-QF-PCR) can be used as an alternative method for prenatal diagnosis of Down syndrome. SD-QF-PCR involves segmental duplications sequences between the test and control chromosomes to detect aneuploidies. Materials and Method: Segmental duplication are two similar sequences with different fragment lengths, located on two different chromosomes.When these segmental duplication regions are amplified, the peak ratio between the two different chromosomes remains 0.9 to 1.1 and the trisomy 21 results in the ratio of 1.4 to 1.6. In this study, we applied SD-QF-PCR method to detect the presence of trisomy 21 in sixty age-matched controls and sixty DS samples. The PCR amplification of segmental duplication regions is done using a single pair of fluorescently labelled primers, the peak ratio between the two different chromosome regions are evaluated. Results: All sixty control samples showed the peaks to range from 0.9 to 1.1 which was suggestive of normal samples while peaks of sixty-five DS samples range from 1.4 to 1.6 which suggested the presence of trisomy 21. Conclusion: Segmental Duplication Quantitative Fluorescent PCR is a sensitive and rapid aneuploidy detection technique hence can be used as a standalone test to detect trisomy 21 as well as other aneuploidies.
Keywords: SD-QF-PCR, Aneuploidies, Trisomy 21, Prenatal Diagnosis