It is now scientifically feasible to use preimplantation genetic diagnosis (PGD) during IVF to screen embryos for genes associated with high breast cancer risks, scientists say.
European researchers presented the results of a major study- as yet the largest in this area of research, at the European Society of Human Reproduction and Embryology’s annual meeting in Istanbul, Turkey. They conclude that the technique can be used reliably so that men and women who carry cancer-causing mutations in their BRCA1 or BRCA2 genes do not pass them on to their children. Female carriers of a mutation in either gene have a 60 to 80 percent chance of developing breast cancer over their lifetimes, and a risk of 30 to 60 percent (BRCA1) or five to 20 (BRCA2) for ovarian cancer.
The PGD procedure allows doctors to identify which embryos carry these genes, and therefore only implant ones that do not, thereby removing mutations from the family tree.
The study looked at 145 cycles of IVF in 70 couples where one partner carried one of the BRCA mutations. A total of 717 embryos were created for these couples and cultured in-vitro for three days- when they would have comprise eight cells- at which point one cell was extracted and tested for the presence of a BRCA mutation.
Overall, 43 percent of the embryos were affected, while 40 percent did not carry the mutations and were considered viable. Using the unaffected, the couples achieved a 41 percent pregnancy rate, or 42 pregnancies in 40 women in total.
“We now believe that this technique offers an established option for those couples seeking to avoid the risk of inherited BRCA in their children”, said professor William Verpoest, from the Vrije University in Brussels, who presented the study.
Speaking to the BBC, Mr. Stuart Lavery, director of IVF at Hammersmith Hospital in London said that the study, published months earlier in the journal Human Reproduction, was “quite an important paper”. He said that knowing that removing that removing “12.5 percent of the whole genetic mass of the embryo” for testing did not affect the embryo’s viability was “huge reassuring”.
In his presentation, Professor Verpoest recognized the debates on the ethics of using PGD to screen for BRCA mutation. Cancers associated with the BRCA mutations occur late in life and therefore options for treating them are constantly improving. “Controversy will still remain over the ethical acceptability of PGD for a susceptible, yet preventable condition”, he said.
BioNews, London
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