Biopsy of the human blastocyst and polymerase chain reaction (PCR) amplification of the beta-globin gene and a dinucleotide repeat motif from 2-6 trophectoderm cells.

Cultured human blastocysts have been biopsied on day 5-6 post insemination and 2-6 extra-embryonic cells from the trophectoderm were removed and their DNA subjected to specific amplification by the polymerase chain reaction (PCR). Simultaneous amplification of part of the beta-globin gene and a dinucleotide repeat sequence has been achieved in a high percentage of cases when using the DNA from both trophectoderm cell biopsies and biopsied blastocysts as template for the PCR. A similar success rate was achieved when serial biopsies were taken from the same blastocyst, thus allowing one cell sample to be held in reserve for use should equivocal results be obtained. Over the entire experimental period (5 months), no contamination was experienced with biopsy or PCR procedures. Following biopsy of the trophectoderm cells all blastocysts had reformed a blastocoele cavity within 3-4 h of the biopsy procedure. Those blastocysts remaining in culture after this time showed a high incidence (78-83%) of hatching and outgrowth.