the HD test on the embryos , and putting only the HD-negative embryos into the woman's womb. The PGD Process PGD is done as part of IVF ( in-vitro fertilization ). IVF is a medical procedure which involves a woman taking medications to cause the body to produce more eggs than normal. The eggs are then collected and fertilized using a sperm sample given by the man. The fertilized eggs are left for a few days to develop into embryos . The embryo is grown in the laboratory for two to three days until the cells have divided and the embryo has about eight cells. One or two cells are removed from each embryo at this stage. Removing cells at this early stage of development doesn't affect the way that the embryo develops. The removed cells from each embryo are then tested genetically to see whether it has the HD mutation. Finally, one or two embryos that don't have the mutation are transferred to the womb to allow them to develop. Any healthy unaffected embryos can be frozen for later use. About two weeks after the embryos are transferred, the woman will have a pregnancy blood test. If the transfer has been successful, pregnancy then carries on like normal. The downside of PGD IVF -- the process of stimulating egg release, collective eggs, fertilizing them outside the body and returning embryos to the womb -- is always a time-consuming and exhausting process. It can also be dangerous, carrying risks of