How Does PGD Work?
PGD requires patients to use in vitro fertilization (IVF) to produce multiple eggs and embryos that will undergo biopsy and genetic testing. The biopsy of the embryos can be performed at different stages. The earliest way of testing the embryos is by studying the polar bodies (small cells consisting of a tiny bit of cytoplasm and a nucleus, formed during maturation of the egg). The polar bodies can be removed and studied to determine the maternal genetic contribution to the developing embryo. Another way of testing occurs three days after the egg has been fertilized in the lab. In this method, one cell from the eight-cell embryo is removed and its genetic material is tested to identify possible defects. Regardless of the type of cell studied, there are two types of testing available. One technique, the polymerase chain reaction (PCR), produces thousands of copies of a specific DNA fragment. The size of the fragment distinguishes the normal from the abnormal gene. Another technique, flu
