The peptide nucleic acids as probes for chromosomal analysis:: application to human oocytes, polar bodies and preimplantation embryos

Peptide nucleic acids (PNA) are synthetic DNA mimics based on an uncharged polyamide backbone, which hybridize with complementary DNA with high affinity and specificity. PNA have recently become recognized as efficient tools for in situ chromosomal identification. In the present study, this new approach has been tried on isolated human oocytes, polar bodies and blastomeres. Using centromeric PNA probes specific for chromosomes 1, 4, 9, 16, X and Y, we tested multicolour labelling PNA reaction on 27 oocytes and 23 blastomeres. Sequential PNA hybridization was performed on five oocytes and combined PNA and fluorescence in situ hybridization (FISH) reactions on two oocytes. Both the rates and the types of abnormalities observed are in agreement with results from previous FISH studies. This preliminary study indicates that PNA probes allow a reliable chromosomal analysis in isolated human oocytes and blastomeres and consequently might provide an interesting adjunct to FISH for diagnostic analysis.