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PGD

This is a powerful technique, once thought to potentially revolutionize IVF, that has not lived up to its promise. It will continue to be used to look for specific gene defects and possibley for sex selection, but will likely be replaced by either proteinomics or microarray technology.

PGD involves biopsy or removal of a single cell from a day 3 / eight cell embryo so that genetic testing can be done on the single cell. This can be used to avoid transferring embryos that are genetically abnormal either due to a known single gene defect or age effects. It can be used to help us understand why IVF is not successful in a particular patient or perhaps help make it more successful for a patient with failed IVF cycles. It can also be done for sex selection (with near 100% efficacy). It plays a role in treating recurrent pregnancy loss when the standard work-up is otherwise negative.

We utilize one of the most experienced outside groups to both biopsy the embryo and to undertake genetic testing on it. This is a powerful technique that is relatively new to the clinical IVF community. It adds several thousand dollars to the cost of an IVF cycle.

It spite of the power of this technique, it is likely to be replaced by better technology in a few years. There are two more powerful techniques on the horizon. The first of these is microarray technology. This involves cutting up the DNA in a biopsied cell into thousands of pieces, replicating these pieces and getting them to attach to a computer chip with known pieces of DNA on it. This can be read and used to identify many variations of genes that are contained in that cell's DNA. This reading can be used to determine whether or not the embryo is chromosomally normal. It will also provide information about other aspects of the embryo like hair color and predisposition to diseases.

An even more exciting technique utilizes proteinomics. This technique is especially exciting in that it does not require biopsy of the embryo. It requires looking at the fluid in which an embryos was growing during its 8-cell stage and identifying the amounts of some of the proteins that were produced by the embryo. This will enable us to know if the embryos is chromosomally normal and perhaps other factors related to implantation potential.

One of the big problems to overcome has to do with the time these newer procedures take. Will PGD, results are obtained quickly enough to undertake a fresh transfer on day 5 or 6. With these newer techniques, the embryos are currently frozen and transfer takes place at a time distant from the cycle. Frozen embryos have a lower pregnancy rate than fresh embryos.