Evaluation of QF-PCR in simultaneous detection of trisomy 21 and monogenic diseases in PGD

Background: Trisomy 21 (Down syndrome) is occurring in one of 700-800 live births. Preimplantation genetic screening (PGS) is a method used in women with recurrent abortions, frequent ART failures and older age pregnancies enabling selection of normal chromosomal embryos which prepares for healthy successful pregnancies. Currently, various methods are used for PGS including FISH, aCGH and qPCR while each one has its own advantages as well as disadvantages. QF-PCR which is extensively used for the prenatal screening of the common aneuploidies can be recommended as a reliable alternative method for PGS due to its relative advantages including speed, low cost and high sensitivity/specificity. In addition, it can be used on embryo for the concurrent detection of single gene disorders through single blastomere biopsy. Objective: Present study was aimed to evaluate the capability of QF-PCR in screening for trisomy 21 on single blastomere biopsies.Materials and Methods: Four STR markers were used to evaluate the ploidy of chromosome 21 using DNA from whole genome amplification (WGA) of single blastomeres from 30 trisomic/disomic embryos. The reactions were optimized in advance using single lymphocytes while the STR markers were also checked for desired heterozygosity in Iranian population.Results: QF-PCR showed a relative capability to screen for trisomy 21 on embryonic samples.Conclusion: Although QF-PCR could be applied for the screening of chromosome 21 trisomy in embryo, due to some limitations including allele drop out (ADO), preferential amplification (PA) and non-specific signals; it will be necessary to take measures for further optimization of the reactions in a larger sample size. In addition, using nested PCR instead of DNA from WGA may decrease the rates of ADO and PA. Finally, the test should be checked in terms of its sensitivity and specificity to make it applicable for clinical application.

کلیدواژه ها:

PGD ، Trisomy 21 ، SGD ، QF-PCR