Preimplantation genetic diagnosis by FISH technique

In couples with advanced maternal age, carriers of genetic disease, carriers of X-linked disease, or repeated abortion, selecting only normal embryos for transfer is essential. Embryos at the six to eight cells stage on day three after egg collection can be processed for embryo biopsy by making a small hole in the zona and one to two embryo cells can be taken out for genetic diagnosis. The biopsied embryos are kept in culture for further development.

The extracted embryo cells are fixed on microscope slides and diagnosis is performed by using specific probes (chromosone pieces) and specialized instruments. At present, chromosones 13, 18, 21, X and Y can be detected. The results can be obtained within one day so that normal embryos can be transferred that day or the following to ensure their further development.