Validity of real time PCR in preimplantation gender determination for single human blastomere

Preimplantation genetic diagnosis (PGD) offers couples who need to avoid having a child affected with a severe genetic disease, an alternative to prenatal diagnosis and termination of an existing pregnancy. One of the main indications of PGD is sex selection to avoid sex-linked genetic disorders. The main objective of the present study was to investigate the feasibility of whole genome amplification (WGA) and real time PCR for sexing of single human blastomere and to confirm the results by sequencing. Forty non-viable embryos were selected for analysis. WGA technique was employed on single blastomeres that were biopsied from embryos and on buccal mucosal cells obtained from five men and five women as positive and negative controls respectively. Whole genomic DNA amplification efficiency from a single human blastomere and from optimized buccal cells was 100 % and the level of amplification reached hundreds fold. The obtained genomic DNAs were then subjected to PCR amplification of the SRY, DYS14 and DAZ genes for gender determination. DAZ sequences correctly identified the gender of all male and female embryos with 100% sensitivity and specificity. However, the obtained sensitivity and specificity for SRY sequences were 92.6% and 100% respectively and the obtained sensitivity and specificity for DYS14 sequences were 100% and 93.8% respectively. The results of the present study prove the feasibility of WGA PCR assay for the detection of specific DNA fragments from single cells and the real-time PCR assay of the multicopy DAZ sequence in single human blastomeres detected correctly the embryo’s gender. This will pave their use in preimplantation gender determination genetic diagnosis.